Add Treeherder to main interests section (1046596)

This work fixes part 2 of Bugzilla bug [1046596](https://bugzilla.mozilla.org/show_bug.cgi?id=1046596).

This adds the Tree Management product to bugsahoy under the general category of 'Dashboards and Reporting' - in case there are any other dashboards or data management products/components which fall under this area of interest later on... Datazilla, etc. I've iterated with the Treeherder team and they have signed off on the concept and implementation.

Here is the appearance after the change:
![bugsahoy_aug15_14](https://cloud.githubusercontent.com/assets/3660661/3935801/1648e03a-249a-11e4-809c-00c0665e3372.jpg)

I also did a bit of trailing white space cleanup on the file during the change. Line 117-118 in the index is part of that, although Github is a bit odd in presentation of that removal.

Tested on Windows:
FF Release **31.0**
Chrome Latest Release **36.0.1985.125 m**