add failing test

- specify the requirements in test class
fix FileNotFoundException(AndroidManifest.xml)

- @RunWith(TestRunners.WithDefaults.class) instead of @RunWith(RobolectricTestRunner.class)
make it work

- implement FragmentTestUtil#startFragment by referencing org.robolectric.shadows.DialogFragmentTest
Merge pull request #457 from msbaek/FragmentTestUtil

I want to add FragmentTestUtil