Highlighting currently accessing GST in MIS App and added date-time-picker to tot_when in Voluntary Teacher of MIS App.

 - Now currently accessing GST in MIS App gets highlighted intuitively

 - Added date-time-picker to ```tot_when``` in Voluntary TeacherMIS App.
 > This filed is specially for adding multiple dates. 
    It is made as combination of *text input box* and *Add Date button*. 
    User need to select one date at a time and press ```Add Date``` button. Then date gets added in the list  maintained just below that field. User can also delete the added date from this list.
 - Some small error fix in start_time and end_time.