Introduce the concept of role-based access for agents.

This will disable the ability for a user to close a ticket when they
have not filled out all of the required fields. Explains the problem to
the user trying to close and directs them to the edit page. Added some
functions to the $ticket class to make it easy to determine the missing
required fields.

This will contain the effective due date of the ticket — either the due date
or the estimated overdue time of the ticket based on the SLA settings. It
will be maintained with ticket updates.

orm: Add greater support for expressions in order_by

This patch adds support for automatic date and time formatting based on a
selection of locale. The locale can default to the system or user specified
language+locale, or can be elected separately. For instance, English
speakers can pick between US, GB, and many other English speaking locales.

This also removes the need of the %timezone table and uses the timezonedb
built into PHP 5.3+. User's can now select from a much longer list of
database and no longer need to deal with the DST checkbox.

Move the attachments to the sidebar, add the concept of language-specific
attachments. Add a sidebar to the front page. De-emphasize the "open new
ticket" button. Add a knowledge base search feature to front page and also
add the concept of "featured" articles and categories on the front page.

Also complete the translation client-side

This reworks the tabs CSS and javascript coding to be more flexible and to
support vertical tabs. (Bootstrap calls this stacked.) The javascript also
allows the URL to include the hash-tag of the last-clicked tab so that the
tab can be automatically shown when the page is reloaded.

Including language-specific attachments