move loggers, etc. for plugins over to a PreInitializationEvent
get rid of global logger in game
update example plugin for new logger changes
Update README.md
Add Guava 16 as a dependency.
Add JUnit, Hamcrest-library, and Mockito as test dependencies.
Add preliminary command interfaces.
Fix an incorrect assertion that getCause() won't return null.
Merge pull request #171 from jacklin213/patch-1

Update README.md