making `cli.proper_case` use a new method that runs through all sources in project.sources, and return the Request's return for the first one that hit OK, or neither did ok, then raise an exception.
making `cli.proper_case` use a new method that runs through all sources in project.sources, and return the Request's return for the first one that
hit OK, or neither did ok, then raise an exception.

Also doing something similar to `cli.pip_install` so that it will try to pip install for all the sources and return the first cmd that worked or the last that didn't work.

nateprewitt/pipenv,kennethreitz/pipenv