Cleaned up constructor reflection code.

* There was a lot of duplicate code and tests between BurstAndroid and BurstJUnit4 for reflecting on constructors, refactored all that into BurstableConstructor and BurstableConstructorTest.
* Replaced all the exception-checking test code with ExpectedException equivalents.
Merge pull request #39 from zach-klippenstein/zachklipp/refactor-constructor-reflection

Cleaned up constructor reflection code.