Fix #440 Add auto recording feature

- Add end time field in talk editor
- Add auto record button in record interface
- Add dialog box if no talk available for auto recording
- Add dialog box if no room selected for auto recording
- Add auto record widget to set up full screen countdown and talk info
  display
- Add flash screen at 1 minute and at 30 seconds mark
- Add code for start/stop recording for each talk that is eligible
  for auto recording

Closes #478