fixed month picker icons in the datepicker
fixed datepicker such that the default date that appears is today if there is no startdate set for the trip, or the startdate of the trip. changing the startdate changes the default date that appears selected in the datepicker. added a Today button to the datepicker that automatically sets the startdate of the trip to Today. official library used is datetimepicker: https://github.com/smalot/bootstrap-datetimepicker. removed previously used bootstrap datetime gem. added the associated css file