Update stopwatch workflow

[RipeFruit08]

Desired behavior:

Switch from three buttons (Start, Reset, Stop) to two buttons

One button that says "Done" that will notify user that a session is being saved. User will be shown what information will be saved and user has decision to accept for decline that saving of that information. If accepts, the data gets saved to CoreData. Otherwise that data gets thrown away and the state of the stopwatch is reset

Other button will change text depending on the state of the application. Default state will show the button as "Start", if the timer is running then the button will display "Stop". (Maybe) if the timer is stopped and time elapsed is non-zero display "Resume"

Obstacle: Figuring out how to have a button with changing text stay in some well defined fixed location and look "nice"

Notes: Buttons will only respond to touch events when necessary. (E.g. when tapping the done button when no time has elapsed don't do anything)

[RipeFruit08]

Portion of adding comments to sessions are complete

[RipeFruit08]

Next step: remove "Set Rate" button from StopWatch view since the ability to set the rate is implemented in the settings tab

[RipeFruit08]

Need to re-think the logic of how time works in the background, or start documenting current implementation