Background is now set in the proper place
Fix bugs introduced by setting the background in the correct place
Change GL clear color to black
Create LevelData to enable levels to be loaded and saved
Merge branch 'develop' into leveleditor

Conflicts:
	core/src/com/sweatyreptile/losergame/screens/TestScrollingLevelScreen.java
Create convenience method for setting the background of a level
Make setting the background even more convenient
Merge branch 'develop' into leveleditor
Generate levelData from an existing level
Export short instead of long class name

When instantiating levels, only the short class name is needed, as only
classes in com.sweatyreptile.losergame.screens work.
Fix up TestLevelScreen for use in testing
Pass assets in and create EntityFixtureDef correctly
Queue entities for creation on level.show() with EntityData
Testing stuff