Feature request: #1476 Favourite tables select box.

This is in reference to my earlier pull request https://github.com/phpmyadmin/phpmyadmin/pull/1095

In this commit:
- Refactored RecentTable class for Favorite Tables.
- Implemented this using Ajax.
- Made a FAQ entry.

Signed-off-by: Ashutosh Dhundhara <ashutoshdhundhara@yahoo.com>