Bug 957122 - Enable more TBPL tests - Calendar tests

Add test_calendar_flick_through_months and re-enable test_calendar_new_event_appears_on_all_calendar_views
Merge pull request #15275 from bobsilverberg/tbpl_calendar_tests

Bug 957122 - Enable more TBPL tests - Calendar tests
Bug 959344 - Disable on TBPL for mac only test_settings_gps.py a=testonly
Bug 949897 - Investigate intermittents in test_cards_view_kill_apps_with_two_apps - Reenable test