Adding hg bookmark display to Agnoster theme

Adding bookmark display to agnoster theme:

![1__tmux_new_-s_hook__tmux__and_attributiontopologyprovider_java_-__storm__-_storm_-____dev_stormpipeline_](https://cloud.githubusercontent.com/assets/1200246/5265591/8be398f4-7a11-11e4-8758-bb3fcfad36be.png)