Added double middle pieces

Added Double Middle pieces for top, right, down, and left for the dirt
and grass tiles.
Added Stone Tiles (read this)

Stone tiles will be used in conjunction with the boundries so the player
has a visible representation of tiles that he cannot jump through. If we
need more stone tiles, just talk to me and i'll whip some up.
-Travis
Merge branch 'grass-dirt-palette'

Conflicts:
	gamefiles/Content/__pycache__/py_clockHunter.cpython-32.pyc
	gamefiles/Content/__pycache__/py_level_logic.cpython-32.pyc