Introduce an option to expose container's port(s). In particular,
it introduces a parameter 'exposed_ports' on creating container.
The value is in the form: ``{"<port>/<protocol>": {}}``. For
example, it can be ``{"80": {}}`` or ``{"80/tcp": {}}``.
The format is designed to align with docker's option 'ExposedPorts'.
If this parameter is provided, Zun will create a security group
for the container. The security group will be populated a set of
rules to open those exposed ports.
This feature is a managed security group feature (Zun manages the
security group of the container). Obviously, it cannot be used
with the 'security_groups' parameter, in which users are responsible
to manage the security group.
Change-Id: Id713ce602dca8e74089d4a5eea8df41ea8784db4
Partial-Implements: blueprint support-port-bindings
44dc51f8df