3 Calendar test cases which are confirmed running smooth on hamachi with v1.3.

1. calendar app modified
   * add today display button and tap method (clean-up issue)
   * add month_view_locator (clean-up issue)
   * add tap_first_event to enter the event edit page (clean-up issue)
   * rename displayed_events_in_xxx_view
         to displayed_1st_event_text_in_xxx_view for reality
   * add new displayed_events_in_month_view method,
     it's for real events(clean-up issue)
   * add _get_events_text_locator_in_month_view for the event_text usage
   * modify _get_events_locator_in_month_view for real events, not event text
2. calendar.event modified
   * add edit button, its tap and wait method (clean-up issue)
   * add delete button and tap method (clean-up issue)