Show user status on the user listing table

The code introduced to convert the database values to PHP values introduced
a bug where the configuration would not be saved.

There was a major goof for osTicket 1.8.0 where the installer created a
`form_id` column in the `%filter` table; however, the upgrader neglected to
add the column. Therefore, users who have upgraded from a version previous
to 1.8.0 will not have the `form_id` column in their database whereas users
who installed osTicket >= v1.8.0 and upgraded will have the column. Since
MySQL has no concept of `ADD IF NOT EXISTS`, this dynamic query will
assist with adding the column if it doesn't exist.

Thanks, http://stackoverflow.com/a/16405301/1025836

Previously only admins and department managers could show assigned tickets
on open queue -even- when the feature is disabled globally. This pull
request extends the same previlege to all agents.

(regardless of the source)

Such images are attached to emails by Lotus Notes. Technically, these images
are valid attachments, although historically osTicket would reject them