Utility to inject username:password into url.
Make the username/password optional

- Thus make it possible to extract a credential-less URL.
Generalized the update remote/origin method.

- Since the two current users have a generic flow, define that as the
  reference method and make it call the stubs that are implementation
  specific.
Integrate the credential passing in push url

- For the integration of the temporary user/password credential feature
  extraction from default remote.
Also allow target_remote to be injected with creds
Makes sense to test that fail, too.
Ignore all virtualenv dirs.
Yet another package renamed.
Yet another python version verified to work

- No harm to keep it this way, for now.