Feature/discard warning + ticket preview enhancements

Add CSV (Excel) export option to ticket search results

Adds a link to the scp/tickets.php page (Tickets) allowing for the export of
the data to CSV file. This is preliminary and still needs a few items:
  * An icon + button CSS definition
  * Support for alternate columns (staff assigned, etc.)

Also add beginnings of complex export support (PDF, JSON  and other
formats
to follow). CSV is fully supported for now.

And for brevity, add a Http::download method to allow for consistent and
browser-independent forced page content downloads

UTF-8 for install

Feature/scp login design 

Support register_globals PHP ini setting from the installer

Looks good. Remember, don't close the feature branch before the pull-request in the future, so we don't have the extra commits in the pull-request.

Approved - minor edits later.

Change href definitions for embedded links in the ticket thread so that the
click will be bounced through a script. This will hide the original referrer
URL where the link originated.

Reviewed: .htaccess for mod_rewrite

The API is implemented for HTTP requests via the api/http.php module.  Where
supported (by Apache), support rewriting URIs from something like
http://domain.tld/api/tickets.xml to
http://domain.tld/api/http.php/tickets.xml, so the explicit usage of the
http.php script is not required.

Review - Add deleteOrphans() utility to the File class to remove unused files

* Thanks for the fix.

Review - Reject tickets from banned emails. 

*Looks good 

Also add a cron job to perform the task on demand
Change the implementation for Ticket::deleteAttachments to call this method
after simply removing all entries from the %ticket_attachment table