Compatibility with InstrumentationTestCase and esperanto

- Have `getName()` return the plain method name if `runTest` is
  currently executing. I thought this was unnecessary because `TestCase`
  accesses the name field directly, but `InstrumentationTestCase` goes
  through the getter.
- Intercept `ActivityTestCase`'s `scrubClass` to prevent it from
  scrubbing proxy class fields that were added by dexmaker.
- Avoid calling `findBurstableConstructor` until we know we're looking
  at a real test class (i.e., one whose `tests()` are `TestCase`s). With
  `GoogleInstrumentationTestRunner`, there's an extra suite in the tree
  of tests passed to `setTest`.
- Add a test which interacts with the target app.
Address feedback
Merge pull request #29 from square/dlubarov.realistic_test

Compatibility with InstrumentationTestCase and esperanto