Support for CursorLineNr

Hi,

You wrote [here](https://github.com/tomasr/molokai/issues/8#issuecomment-16748656) that you may add support for CursorLineNr if someone will send a pull request a fix and will ensure it doesn't break older versions. Here is such a pull request. I checked it with vim64 and vim72, and as far as I could notice, it doesn't seem to make any change, nor there is an error message (this is the desirable behaviour).

Júda