a. Given a program, allowing teacher to be associated to specific timings of a program.
b. Add field timings_str to teacher_schedule table, to de-couple it from program's display_str

Pending -
1. Need to do Point a. (above) given a teacher.
2. Need to update teacher_schedule timings_str depending upon how user fills the announced_timings for the program, when the program is getting announced.
Merge remote-tracking branch 'origin/amit' into amit