Fixed code standards violation in BaseSprite

Use of no brace if-else.
Typo fix in TankCameraController's javadoc
Background layer now drawn
Merge branch 'Canfield-Staging' into Canfield
Eliminated need to use wildcard w/ Sprite

- Entity-based sprites should inherit from AbstractEntitySprite<?>,
while non-entity-based sprites should inherit directly from Sprite
Sprite.isEntityDisposed -> Sprite.isDisposed

This may delegate to Entity.isDiposed, or it may not, depending on the
needs of the sprite
Resolved merge conflicts
Network tanks now hide themselves when the isHidden flag is set
Fixed tank draw mistake
Fixed tank camera controller attach bug
Fixed tank being drawn twice
Fixed incorrect comments in TankSprite
Local tank now becomes translucent when hidden in trees

Thanks to Aaron for suggesting this.
Increased Sprites.java test coverage
Added NetworkTankControllerTest

- Moved controller tests to correct packages
Added more unit tests; Cleaned up TankSprite
Removed the deprecated DefaultSprite
Increased unit test coverage
Continued NetworkObserver-related implementation
Switched multiple references from AbstractEntitySprite to Sprite