* Added an Empty Content project to the current solution for storing images, sound, and other media.

***REQUIRED*** for handling all content used in the project.
* Modified the RpgGame class for image rendering purposes.
* Added a (ghetto) sample background for image for testing.
* Renamed the Rectangle class to "Hitbox" class to avoid ambiguity and conflict with XNA's built-in Rectangle class (which is used for drawing).
* Renamed the RectangleTest to "HitboxTest" for consistency. (Matches with Hitbox class).
* Added Jump feature to the IController and HumanController classes. (Enemies cannot jump by default.)
* Implemented the Draw functionality to the RpgGame class (the main class).