Fixup b07b4b2: client secret needed for password grant type

Unlike before, the public authenticator interface
makes no accommodation for its storage, so pass it
explicitly into the auth method. Like before, only
the local version is stored.
Fixup #16: fix missing test fixture reference in project file
Stop using build scheme target launch arguments for test config

This includes CI tests as well. Rather, remove the
entire separate build scheme for CI tests. Use
plists that switch with the build configuration
(debug or not).

The next commit contains the updated fixtures for
the CI config changes.
Update fixtures for updated CI config