Previous tests have worked by pure chance since the client and server
ran on the same host; the server picked up the credentials created by
the client login.
Extend the gating tests and add a new integration test which is further
capable of exercising the remote code.
Note that fixing authentication support requires adding a new
`--authfile` CLi flag to `manifest inspect`. This will at least allow
for passing an authfile to be bindings. Username and password are not
yet supported.
Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>