Shield
Imported NGUI 2.0.7
Added in game pause menu to my scene, and as a prefab. Press Esc to open.
Dimmed pause screen
Merge remote-tracking branch 'origin/dkharley'

Conflicts:
	Assets/Prefabs/Cube.prefab
	Assets/Prefabs/SideThruster.prefab.meta
Added UI to main scene.
Added thinner trigger collider for "Platform" tag on ramps, no more flipping. Collision collider remains the same.
Fixed shield behavior, made shield graphic smaller.
Redid vehicle inputs so that scene reloading doesn't cause thrusters to get stuck.
Made ramp rotation collider thinner.