add js code for live translation feature of transifex

https://github.com/openSUSE/osem/issues/99

All sub-pages of the app need to be scanned and then strings found need to be translated in the editor:
https://www.transifex.com/projects/p/osem/live/#en/events.opensuse.org

As soon as translations are published (gear icon in top right corner -> Take Live -> Publish) they automatically appear in the app.

Introduces a language selector on bottom-right corner.
![screenshot-osem - chromium-6](https://cloud.githubusercontent.com/assets/4322737/4222046/9756688a-390f-11e4-9b18-375aa75648ba.png)
You will have to put this into the application layout file. There is no sane way to access env variables from the asset pipeline...