The test structure is now provided by a JS API, that is used by all things that run tests. Also, the tests can be run manually by tapping a button in the ReactTests app.
The deleteTestFiles() function is now added to the Realm object, so that it's easy for the RPC module to handle this as well. We can only do this in testing environments in the future.
In the case of test failures, a TestFailureError object is thrown, which removes the last two stack frames so the true source of the failure is revealed to the native code.
Clicking on a failure in the Xcode sidebar will take you to exactly where it occurred now.
Fixes#28
