bugfixes, changes, things, leap motion:

- fixed a bug where the icons on the announce page were too small for comfort #24
- completely rewrote how controllers handle leapmotion related things.
- added buttons for switching from burn-up to burn-down on the burn-up page.
- added task model.
- added a serializer for parsing tasks in stories.
- show each task associated with each story and their corresponding state (completed, !completed).
- rewrote story serializer.
- added a "currentController" used by leapmotion to bubble actions from the Application controller to the right page.