[Exist-development] Responsive documentation app

[<wol...@ex...>]

I completed what Loren started some time ago and migrated the documentation app to a responsive design, so please get out your iPhones, androids or tablets and enjoy

http://www.exist-db.org/exist/apps/doc/

The main menu is now a bootstrap navbar, but with tweaked CSS to make it look like the original eXist-db design.

Wolfgang