Fixes:

- Fixed the issue when "Edit Reply" form wouldn't open if TinyMCE editor was set to "Text" previously.

Updates:
- Minor front-end template updates (both .php and .css)
- Better user selection field in ticket list filters, ticket creation and ticket editing based on Select2 jQuery plugin.

New:
- Added new post-installer for websites with over 300 registered users (at the time of activating the plugin).
