Prevent text highlighting

Clicking on the detector would inadvertently highlight text

![screen shot 2014-08-07 at 1 37 33 pm]
(https://cloud.githubusercontent.com/assets/6556190/3848947/b29ad708-1e74-11e4-8ad8-58de419167d8.png)

Added css class that does nothing on user selection. Applied class to center div

![screen shot 2014-08-07 at 2 01 07 pm](https://cloud.githubusercontent.com/assets/6556190/3849121/0f855cbc-1e76-11e4-845f-c6f8fa4a3ff8.png)

![screen shot 2014-08-07 at 1 38 38 pm](https://cloud.githubusercontent.com/assets/6556190/3849137/27fc54d0-1e76-11e4-8652-f4e2228ebb4c.png)

Users can still click the info button to the top right of detector. This change only stops text on the center div from being selected.