Allow empty variable - or whatever objects return

Force target selection on filter form
Add minor code improvements

Change the with of the info table

Example use case %staff.name  %team.name ... etc.

Change %assigned to mean assignees (staff or/and team)

* Change table name from ost_email_filter* to ost_filter*
* Add patch for target field.

* Collapse date settings into system settings.
* Move auto-cron setting to emails settings page.
* Move clickable urls setting to tickets settings page.

 * Collapse Department into Staff tab.
 * Add a new 'Manage' tab - home for managing items, lists..etc.
 * Collapse Help Topics into Manage tab.
 * Move SLA and API from Settings to Manage tab.

When reading data from /dev/urandom and friends on *nix systems with the
open_basedir setting enforced.

This will help distinguish between the knowledgebase part which encompasses
FAQ's and canned responses, and the FAQ part which contains the articles
detailing frequently-asked-questions.

* Auto rehash MD5 based passwords