create TaskController and associated tests, some more rails 4 related stuff

* https://www.pivotaltracker.com/story/show/66911680

[Finish #66911680]
Updates based on PR comments:
- use haml, remove unused views and associated tests
- clean up/enhance TasksController and associated tests

- https://github.com/joshclick/RailsTodo/pull/3
- https://www.pivotaltracker.com/story/show/66911680

[Fixes #66911680]
Updates #2 based on PR comments:
- fixup controller spec, add json spec helper
- remove unused helpers and associated spec

- https://github.com/joshclick/RailsTodo/pull/3
- https://www.pivotaltracker.com/story/show/66911680

[Fixes #66911680]
Merge pull request #3 from joshclick/create_task_controller

create TaskController and associated tests, some more rails 4 related st...

Good Job Click!