ui: Fix large image display

Fixes oversize image display to be resized in both the ticket thread and
the redactor editor in (at least)

  * Ticket-view boxes
  * Client new-ticket form
  * Staff new ticket
  * Page add/edit
  * FAQ add/edit
  * Canned response add/edit

Fixes osTicket/osTicket-1.8#247
Merge pull request #251 from greezybacon/issue/247

ui: Fix large image display

Reviewed-By: Peter Rotich <peter@osticket.com>