Merge pull request #39 from zach-klippenstein/zachklipp/refactor-constructor-reflection

Cleaned up constructor reflection code.
Added support for discovering public injectable ("Burstable") fields in addition to parameterized constructors.

There was a lot of duplicate code and tests between BurstAndroid and BurstJUnit4 for reflecting on constructors, refactored all that into BurstableConstructor and BurstableConstructorTest.