Add UPGRADING.txt file to describe post automated upgrade activities

The upgrader can't (and shouldn't) do everything necessary to complete an
upgrade. The adminsitrator will need to take care of a few extra tasks that
are outlined in the UPGRADING.txt file. One of the items includes removing
source code no longer used in the 1.7 codebase. A script is shipped (Unix
only) that allows an administrator to automatically clean up all old source
files that are no longer used.

UPGRADING.txt

+Welcome to osTicket 1.7
+=======================
+Some tasks are better left to a system administrator rather than a mindless
+upgrade script. These are those remaining things that we'd rather you take
+care of:
+
+  * Verify that your attachments have been successfully migrated to the
+    database and removed from your server's filesystem. Once you're
+    comfortable that they're all migrated, and that the remaining files are
+    all failed uploads or orphans from deleted tickets, remove the folder
+    where attachments were uploaded to.
+
+  * Remove codebase files no longer utilized in osTicket 1.7. If you have
+    console access to your server, a codebase-cleanup.sh script is provided
+    for you in the setup/ folder to help you automatically take care of this.
+    * api/api-sample.zip
+    * api/do.php
+    * api/email.txt
+    * api/email.xml
+    * api/pipe2.php
+    * api/post.php
+    * api/test.txt
+    * api/xml.php
+    * images/bg.gif
+    * images/button.jpg
+    * images/fibres.png
+    * images/home.gif
+    * images/icons
+    * images/lipsum.png
+    * images/logo2.jpg
+    * images/logo.jpg
+    * images/logo.png
+    * images/logout.gif
+    * images/my_tickets.gif
+    * images/new_ticket.gif
+    * images/new_ticket_icon.jpg
+    * images/new_ticket_title.jpg
+    * images/poweredby.jpg
+    * images/rainbow.png
+    * images/refresh_btn.gif
+    * images/ticket_status.gif
+    * images/ticket_status_icon.jpg
+    * images/ticket_status_title.jpg
+    * images/verticalbar.jpg
+    * images/view_closed_btn.gif
+    * images/view_open_btn.gif
+    * include/class.bkmailfetch.php
+    * include/class.msgtpl.php
+    * include/class.sys.php
+    * include/client/index.php
+    * include/client/viewticket.inc.php
+    * include/ost-config.sameple.php
+    * include/settings.php
+    * include/staff/api.inc.php
+    * include/staff/changepasswd.inc.php
+    * include/staff/dept.inc.php
+    * include/staff/depts.inc.php
+    * include/staff/editticket.inc.php
+    * include/staff/mypref.inc.php
+    * include/staff/myprofile.inc.php
+    * include/staff/newticket.inc.php
+    * include/staff/premade.inc.php
+    * include/staff/reply.inc.php
+    * include/staff/smtp.inc.php
+    * include/staff/viewticket.inc.php
+    * scp/css/autosuggest_inquisitor.css
+    * scp/css/datepicker.css
+    * scp/css/main.css
+    * scp/css/style.css
+    * scp/css/tabs.css
+    * scp/images/alert.png
+    * scp/images/bg-login-box.gif
+    * scp/images/icons/email_settings.gif
+    * scp/images/logo-support.gif
+    * scp/images/minus.gif
+    * scp/images/ostlogo.jpg
+    * scp/images/pagebg.jpg
+    * scp/images/plus.gif
+    * scp/images/refresh.gif
+    * scp/images/tab.jpg
+    * scp/images/view_closed.gif
+    * scp/images/view_open.gif
+    * scp/js/ajax.js
+    * scp/js/autolock.js
+    * scp/js/bsn.AutoSuggest_2.1.3.js
+    * scp/js/calendar.js
+    * scp/js/datepicker.js
+    * scp/js/tabber.js
+
+  * Remove the setup/ folder. This contains code you won't need for a live
+    ticketing system.

setup/cleanup-codebase.sh

+#!/bin/bash
+
+find_root() {
+    local root=".";
+    while [[ ${#root} < 20 ]]; do
+        [[ -f "$root/main.inc.php" ]] && break
+        root="$root/.."
+    done
+
+    [[ ! -f "$root/main.inc.php" ]] && exit 1;
+
+    pushd . > /dev/null
+    cd $root
+    pwd -P
+    popd > /dev/null
+}
+
+root="$(find_root)"
+if [[ ! -f "$root/main.inc.php" ]]; then
+    echo "!!! Unable to determing codebase root."
+    echo "!!! Try running this inside the codebase path."
+    exit 1;
+fi
+
+while read file; do
+    if [[ -n "$file" && -f "$root/$file" ]]; then
+        echo "Cleaning $file";
+        rm "$root/$file";
+    fi
+done <<< "
+api/api-sample.zip
+api/do.php
+api/email.txt
+api/email.xml
+api/pipe2.php
+api/post.php
+api/test.txt
+api/xml.php
+images/bg.gif
+images/button.jpg
+images/fibres.png
+images/home.gif
+images/icons
+images/lipsum.png
+images/logo2.jpg
+images/logo.jpg
+images/logo.png
+images/logout.gif
+images/my_tickets.gif
+images/new_ticket.gif
+images/new_ticket_icon.jpg
+images/new_ticket_title.jpg
+images/poweredby.jpg
+images/rainbow.png
+images/refresh_btn.gif
+images/ticket_status.gif
+images/ticket_status_icon.jpg
+images/ticket_status_title.jpg
+images/verticalbar.jpg
+images/view_closed_btn.gif
+images/view_open_btn.gif
+include/class.bkmailfetch.php
+include/class.msgtpl.php
+include/class.sys.php
+include/client/index.php
+include/client/viewticket.inc.php
+include/ost-config.sameple.php
+include/settings.php
+include/staff/api.inc.php
+include/staff/changepasswd.inc.php
+include/staff/dept.inc.php
+include/staff/depts.inc.php
+include/staff/editticket.inc.php
+include/staff/mypref.inc.php
+include/staff/myprofile.inc.php
+include/staff/newticket.inc.php
+include/staff/premade.inc.php
+include/staff/reply.inc.php
+include/staff/smtp.inc.php
+include/staff/viewticket.inc.php
+scp/css/autosuggest_inquisitor.css
+scp/css/datepicker.css
+scp/css/main.css
+scp/css/style.css
+scp/css/tabs.css
+scp/images/alert.png
+scp/images/bg-login-box.gif
+scp/images/icons/email_settings.gif
+scp/images/logo-support.gif
+scp/images/minus.gif
+scp/images/ostlogo.jpg
+scp/images/pagebg.jpg
+scp/images/plus.gif
+scp/images/refresh.gif
+scp/images/tab.jpg
+scp/images/view_closed.gif
+scp/images/view_open.gif
+scp/js/ajax.js
+scp/js/autolock.js
+scp/js/bsn.AutoSuggest_2.1.3.js
+scp/js/calendar.js
+scp/js/datepicker.js
+scp/js/tabber.js
+"