Merge pull request #17 from BU-CS673/production

Updating Backend branch to match Production.
Merge pull request #23 from BU-CS673/Canfield

Canfield -> Graphics
Merge pull request #24 from BU-CS673/graphics

Graphics -> Production
Merge pull request #27 from BU-CS673/production

Updating to most recent Production merge.
Merge pull request #29 from BU-CS673/backend

Backend
Began standardizing and testing draw() commands for Entities and
subclasses.
Added DefaultSprite class for vanilla Entity sprites. 
Simplified Entity and subclass drawing. 
Created mockup tests for Damageable interfaces for several Entity
subclasses.
Merge pull request #32 from BU-CS673/Canfield

Canfield -> Graphics
Merge pull request #30 from BU-CS673/Aaron

Aaron -> backend
Merge pull request #33 from BU-CS673/graphics

Graphics -> Production
In the process of modifying TankSpriteTest, which is failing after merge.
Added Graphics constructor to TankSpriteTest, was failing when run on its own!
Modified package structure to make world classes easier to find. Removed
parametric Entity constructors and replaced with a setParams method.
Moved unit testing default parameters to EntityTestCase and reworked all
Entity unit tests to be more concise. Moved all Entity unit testing over
to MockSprite and removed DefaultSprites from current use.
Removed world.entity.base package and moved contents one level up, to
world.entity.
Added placeholder for GrassSprite, RoadSprite, TreeSprite pointing at
the default texture.
Merge pull request #36 from BU-CS673/Aaron

Aaron
Merge pull request #37 from BU-CS673/backend

Backend -> Production
Merge pull request #38 from BU-CS673/production

Production -> Graphics
Fixed conflicts w/ Graphics branch