Revert "Revert "Corrected DrawLayers, fixed most Tank tests""

This reverts commit 5f4e374ddbabc0fb1c88bb098d64ec6a5f9dcbb5.
Merge pull request #334 from BU-CS673/Aaron

Corrected DrawLayers, fixed most Tank tests
Merge branch 'production' into pmd-261

Conflicts:
	bubolo/test/bubolo/world/entity/concrete/TankTest.java