Codemirror 4.2 upgrade and styling changes

Updated to codemirror 4.2

https://bugzilla.redhat.com/show_bug.cgi?id=967096

Before:
![screen shot 2014-05-21 at 11 52 24 am](https://cloud.githubusercontent.com/assets/1287144/3292308/cb003e56-f58d-11e3-9fcd-b5857e8449b6.png)

After:
![screen shot 2014-05-21 at 11 52 01 am](https://cloud.githubusercontent.com/assets/1287144/3292307/caf64d56-f58d-11e3-9f44-6e0859242aab.png)