Store colors for modules in memory

ATM whenever bows is required it generates a new color for the requiring context, regardless of module name. I added a `moduleColorsMap` to look up colors for already used modules.

E.g.:
![screen shot 2014-08-18 at 13 09 55](https://cloud.githubusercontent.com/assets/436347/3950606/5a740fde-26c8-11e4-82a3-5313f4f9a215.png)

becomes

![screen shot 2014-08-18 at 13 10 22](https://cloud.githubusercontent.com/assets/436347/3950607/6416d3dc-26c8-11e4-851c-8288d3adff9a.png)