Enable port bindings

Set up nbetworking ports for the following use cases:

* bind the same port between host and container
* bind a specific host port to a different container port
* bind a random host port to a specific container port

Signed-off-by: baude <bbaude@redhat.com>

Closes: #214
Approved by: baude

libpod/options.go

@@ -584,7 +584,7 @@ func WithNetNS(portMappings []ocicni.PortMapping) CtrCreateOption {
 		}
 
 		ctr.config.CreateNetNS = true
-		copy(ctr.config.PortMappings, portMappings)
+		ctr.config.PortMappings = portMappings
 
 		return nil
 	}