Add a vertical color bar based on nick

I've been playing with adding some color to messages based on nick. For me, join/part messages are more emphasized then chat messages currently. This change highlights chat a bit more, plus makes it easier to distinguish who's talking. Screenshots:

![screen shot 2014-06-04 at 17 10 53](https://cloud.githubusercontent.com/assets/3000200/3253137/184644aa-f1d1-11e3-8c9b-20fb63c9c9d2.png)

![screen shot 2014-06-04 at 16 53 45](https://cloud.githubusercontent.com/assets/3000200/3253178/f2baa950-f1d1-11e3-85fe-8aec947a7c7d.png)

Tested on chrome, firefox and IE9.