Coded the functionality for booking a reservation, and updated tests.

Filled submit button action listener with code testing for blank fields and such.
Linked together the gui and controller making it possible to enter a reservation into our database from the gui.
Changed checkAvailability method in controller as I discovered a bug.
Added several tests to further make sure everything works.
Merged CheckAvailbilityTest into ControllerTest as it was a test class working on the controller.