Strips makefile target for shortcirtuing tox install
Strips makefile target for shortcirtuing tox install

This has been a headache for CI, one method works in CI and doesn't seem
to work consistently when being executed via bundletester. (You get one
env, but not the other) Instead of fiddling with the Makefile again and
again, make both dependent on tox, execute the same isntall line, and
roll on.

If someone has some better Makefile fu than I do, please contribute a
patch to fix my janky makefile before i give up and write it in grunt.

chuckbutler/docker-charm,chuckbutler/docker-charm