Working jQuery Mobile frontend for mobile devices

* Added mobile device detection PHP library
* Call PHP library to decide which theme to use
* Added theme as a configuration option into global config
 * Selectable Desktop theme (default: mmcFE)
 * Selectable Mobile theme (default: mobile)
 * Disable mobile theme support entirely

**NOTE**: This requires updates to the `global.inc.php` so please check
the dist file and update your config before filing a new issue!

Addresses #25
Merge pull request #263 from TheSerapher/issue-25-mobile-ui

Working jQuery Mobile frontend for mobile devices