Fix bad query from remote users without email

If a remote user is found by name and does not have an email address, a bad
SQL query would be generated
Correctly process email tickets for existing users

If a ticket is created via email for an existing user, under some
circumstances, no user will be associated with the new ticket.
oops: Don't crash on setting Return-Path
Merge pull request #588 from greezybacon/issue/526

Correctly process email tickets for existing users

Reviewed-By: @rougeAU
Reviewed-By: @syscom2
Reviewed-By: @centoasa
Reviewed-By: @vhadjisophocle
file: Use the database to save files as a failsafe
file: Fix saving backend char

Because the file type normally defaults to the system default (for fetched
emails at least), the backend char was not saved, because the file type char
was left at the system default. Therefore, if a file is saved to a backend
other than the default (in the database), the data will likely be saved to
the backend, but the file metadata will reflect the incorrect backend.

The only reason the file type char was not defaulted in the
AttachmentFile::save() method was for the migration process from osTicet 1.6
to osTicket 1.7. This is mitigated by passing `false` specifically from the
migration task.

Since otherwise the file type char is now set, the backend char is now saved
with the file metadata.
oops: Fix hover and download of inline images (again)
Only add emailed collaborators if we have a positive match on delivered to
email.

This is necessary to eliminate possible loop when an email is sent to a
virtual/aliased address. Not all mail servers add delivered-to header!
Expose staff's signature as possible variable in collaborator's template
forms: Export textual name for custom list fields
forms: Require 'name' for custom lists
Merge pull request #604 from protich/feature/collaborators+aliases

Only add emailed collaborators if we have a positive match

Reviewed-By: Jared Hancock <jared@osticket.com>
Merge pull request #605 from protich/issue/collabs-notice-signature

Expose staff's signature as a variable in collaborator's template

Reviewed-By: Jared Hancock <jared@osticket.com>
oops: Fix display of forgot-my-password link

Reported by @ntozier
Use up-to-date user/staff name instead of poster when displaying ticket thread

Join to staff/user tables to get current name when fetching thread entries.
Merge pull request #608 from protich/feature/poster-name

Use up-to-date user/staff name instead of poster when displaying ticket thread

Reviewed-By: Jared Hancock <jared@osticket.com>
Use the company name for the copyright.
Preserve inline image floating in ticket thread
Merge pull request #586 from protich/feature/copyright

Use the company name on the copyright notice.

Reviewed-By: Jared Hancock <jared@osticket.com>
Merge pull request #611 from greezybacon/issue/forgot-my-password

oops: Fix display of forgot-my-password link

Reviewed-By: Peter Rotich <peter@osticket.com>