TasksController: Only have level+1 tasks
Cleanup v 0.1
	No new features, but lots of polishing, refactoring, etc.
	- Thanks to Simplecov I identified a number of edge cases I hadn't tested for.
		Specs are very thorough now. Through the additional specs, I uncovered
		a number of bugs, mainly affecting dates & deadlines.
	- Refactored & reorganized some controller code and helpers to
		application_controller and application_helper.
	- JS enforces some validations for task settings.
	- Added the gem Timecop, which has made it immensely easier to write specs
		to handle time-sensitive code.