[0.5.0] Responsive template

PR summary:

- New Responsive theme, Started here: #46
- New Slideshow Core Widget with demo slides
- New test page and a widget listing all form elements
- Now using semantic html5 tags
- Navigation identity
- Fix #53 and #56

Screenshot below:

![theme](https://cloud.githubusercontent.com/assets/2228236/3008929/cb0d5e5e-ded8-11e3-97ad-a7e370e90070.png)