Update API to 0.5.1

Make target-to-initiator authentication settings settable via the API.

Signed-off-by: Andy Grover <agrover@redhat.com>
Implement changes in API 0.5.1

Signed-off-by: Andy Grover <agrover@redhat.com>
Fix pychecker warnings

Signed-off-by: Andy Grover <agrover@redhat.com>