build: mozilla tree parsing: fix release tags; add simple tests; use argparse
the underscore was in the wrong position, and wanted FIREFOX_nn__RELEASE instead.

(integrated from komodo (trunk) change 82201 by marky)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@13706 b87d16e7-d29f-4ee1-b5ec-817d645d335f