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.

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**