python-setuptools on OctoPi is quite old and trying to update in a local virtualenv apparently CAN cause problems (we had this with python-serial too a while back), so a backwards compatible solution is better here.
The only translation that is going to be bundled with OctoPrint for now will be .de, if at all. The reason simply being that this is the only translation I can update myself and hence guarantee a good user experience for.
setup.py now offers two new commands, babel_bundle and babel_pack, with which translations for plugins and core OctoPrint can be automatically bundled or packed as language packs once compiled. This should make sharing translations quite easy in the future.
Otherwise we get import issues during build since the octoprint module depends on the dependencies already being present what they obviously can't be at the beginning of setup.
