Mock modules properly in test runner

As an added bonus, the jasmine web interface now groups tests by file.

Test Plan:
grunt test passes on b2507066, the parent of 566f8b2e (which committed a workaround for buggy module mocking).
Have faith in var hoisting
Merge pull request #584 from spicyj/mock

Mock modules properly in test runner.
Add back mocking removed to make ReactEventTopLevelCallback-test pass.

This is a partial reversion of commit 9937f0c8bd.
Merge pull request #586 from benjamn/reinstate-ReactEventEmitter-mocking

Add back mocking removed to make ReactEventTopLevelCallback-test pass.
Move __owner__ off of props
Merge pull request #575 from spicyj/owner

Move __owner__ off of props