Bug 1068765 - Add support for mochitest-jetpack & tweak WebGL regex

This adds support for the new Jetpack job which makes use of the
Mochitest harness & adds support for the desktop Web GL jobs
that have a job name that is different from their Android variants.

Treeherder equivalent of:
https://hg.mozilla.org/webtools/tbpl/rev/cac32f935b5d