Remove Task Details screen

[chuckbjones]

I would like to merge the functionality of the individual task screen into the main list screen. Then we could remove that screen entirely.

[ginatrapani]

Agreed we should do this. You should be able to perform actions on a task without tapping through to a task details screen.

Ideally it would work the way Android does: select a task and a contextual action menu becomes available. Select multiple tasks, same deal.

[ginatrapani]

Superseded by #172