Add wrap guide to atom theme

![screen_shot_2014-03-04_at_15_09_24](https://f.cloud.github.com/assets/431892/2324423/fdd8bb30-a3c8-11e3-9ae6-27c44a2779a0.png)

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It can be removed by disabling the [wrap guide](https://github.com/atom/wrap-guide/) package.