Work on #8

Support Nightly 32 and 33 as a single graph. I think the easiest way to support other channels is to have a little "Nightly/Aurora" selector at the top of the page, since for any given channel there won't be more than one version per build-date.
That would be nice. Maybe style the buttons differently depending on which is active? Or just have a label at the top? Another option is to have a drop-down menu.