This patch suggests that old attachments in the `upload_dir` can be located
and left alone when upgrading away from osTicket v1.6. Later, via the `file`
command line applet, the attachments can be migrated into the database, or
to the new filesystem plugin after it is installed with:

    php manage.php file migrate --backend=6 --to=D

This allows attachment migration to be retried in the event it failed for
any reason.

(rather than deleted after install)

Files _MUST_ be readable by Apache or IIS in order for the attachment
migration to complete and properly keep all attachments between osTicket 1.6
and 1.7

We should move initial data out of the install SQL file, which will make way
for a few things:

  * Internationalization -- which breaks the migrater model currently.
        Moving the data outside the install script makes it translatable
        without changing the SQL hash
  * Review -- Migrations which add more data don't highlight new features
        that need review to the adminsitrator

And provide a shell script to remove codebase files no longer used in
osTicket 1.7