Merge pull request #80 from jentfoo/master

Reduced code duplication by creating an abstract class that can be used for SubmiterExecutor's
Couple unit test fixes/improvements
These have already been fixed in the 2.0.0 branch I believe, but since we don't know when that will be released, these are for 1.3.0
Small unit test improvements to get a little more code coverage
Added a more efficent immediate future implementation.
By not depending on the SettableListenableFuture we can avoid synchronization on .get calls, and with calling of listeners.
Fix for two checkstyle warnings I missed before pushing
I decided to just make these top level classes so that FutureUtils does not become bigger.
Code duplication reduction for new ImmediateFuture unit tests
Merge branch 'master' into RateLimitingExecutor