Adding styling to bash powerline and some extra fields in the prompt

Hey there I have added some nice styling to the bash-powerline.
you should consider to merge it to your branch.

![screenshot from 2014-02-09 16 02 34](https://f.cloud.github.com/assets/877942/2121461/b976fa36-91e6-11e3-869b-de49e640e284.png)