Update tests for Robolectric changes

* Creates `MapzenGPSPromptDialogFragmentTest`
* Migrates dialog fragment tests from `ItemFragmentTest` to `MapzenGPSPromptDialogFragmentTest`
* Fixes failing test for dialog cancel.
* Fixes failing test by replacing spy with test menu in `BaseActivityTest#openingSearchView_shouldHideOverflow()`
* Removes `BaseActivity#getActivityMenu()` (no longer used)