stop button changes to back once the timer finishes. vibration when the time changes to break time and the other way round
Notification Fixed
Fixes timer still running in background, even after stop button pressed.
Improved running timer UI.
Updated hours to 2 digits, for consistency.
Updated study/break to only accept minutes. Added validation to fields (if field blank, set value to 0).
Removed unused method. No longer needed.
Validation: ensure all necessary fields are filled out.
Validation: ensure all necessary fields are filled out.
Added background colours for different timers, to allow the user to distinguish easily.
Merge branch 'improveTimerUI'

Conflicts:
	StudyTimer/src/main/java/aston/team4/studytimer/TimerActivity.java