Boardindex overhaul

some changes for the board index.
- moved the childboard_row as child to it's parent. 
- improved mobile device support (removed description and boardmods), added an icon similar to the message index...)

In short: my previous attempt (online at elkarte.net) to restyle the board index was a mistake:
- too many useless infos
- inconsitent with the message index
- various badly aligned elements.

Screenshot attached.

![boardindex](https://f.cloud.github.com/assets/1027992/2399897/e0b2a840-aa03-11e3-9cad-85ba8cc6b49e.png)