Bug 1077679 -  Update the resultset icon colors post-bootstrap 3.2

This fixes Bugzilla bug [1077679](https://bugzilla.mozilla.org/show_bug.cgi?id=1077679).

In it we re-implement the desired glyph color for the resultset icons and do so in a way that insulates them from future bootstrap updates. We already had a `btn-dkgray` at `7c7a7d` (124,122,125) we could have theoretically used. But the landed color for the resultset icons was different enough at (102,102,102), that it seemed to make sense to stick with Ed's approved color - which is `#666`.

There is a `result-set-buttons` parent class which encompasses some of these icons which need the change, but not all. So it seemed to make sense to create another child btn class, `btn-resultset`.

Here is a before and after:

![resultseticonscurrent](https://cloud.githubusercontent.com/assets/3660661/4513012/22b7d028-4b47-11e4-8341-f2e7885ea396.jpg)

![resultseticonscorrected](https://cloud.githubusercontent.com/assets/3660661/4513014/24bf6cb4-4b47-11e4-862b-0999e6e37987.jpg)

Everything seems to appear correctly on both browsers I've tested with a local server.

Tested on Windows:
FF Release **32.0.3**
Chrome Latest Release **37.0.2062.124 m**

Adding @wlach and @camd for review.