Add settings page

This pull request add a new settings page accessed by an icon on the top left corner.
This new settings page currently only have one settings:
 * Download location: Set the movie download location (default: system temporary folder)
I plan to add another one to not delete the movie after they are watched.

I added a new App.settings object that manage user settings in the localstore as well. This feature was requested by many of my friends, hopefully it will be usefull to the upstream.

Preview:
![screenshot - 140314 - 02 15 29 am](https://f.cloud.github.com/assets/1420974/2418365/a967564a-ab40-11e3-9f40-3e264f10ef99.png)