Rename type Port to ContainerPort

Sadly I had to do this by hand - I just could not get gorename to fix up
users of it.

pkg/constraint/constraint_test.go

@@ -26,7 +26,7 @@ import (
 func containerWithHostPorts(ports ...int) api.Container {
 	c := api.Container{}
 	for _, p := range ports {
-		c.Ports = append(c.Ports, api.Port{HostPort: p})
+		c.Ports = append(c.Ports, api.ContainerPort{HostPort: p})
 	}
 	return c
 }