[#33855] Pagination Unit Tests

http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33855&start=0

## More Details
Add an optional Application param to the constructor to allow us to unit test things which depend whether we're in the site or the administrator section of the CMS. Added a couple of extra unit tests to demonstrate this improved functionality

## Testing
Check pagination continues to work in front and backend. Observe unit tests still pass.