use bootswatch theme lumen

Used bootswatch theme lumen (http://bootswatch.com/lumen/). Needs a lot of customizations of course, but this is what waartaa looks with the new theme:

![screenshot from 2014-03-14 03 31 13](https://f.cloud.github.com/assets/1932760/2415872/1b6f9a22-aafb-11e3-8248-68258940abf1.png)