automatically remove container via -rm

add AutoRemove to HostConfig
add -rm flag to docker run
add TestRunAutoRemove to test -rm
docs: add -rm to commandline/command/run
add hostConfig to container monitor
make monitor destroy the container via -rm

This adds support for automatically removing a container after it
exits. The removal of the container is handled on the server side.

runtime.go

@@ -174,7 +174,8 @@ func (runtime *Runtime) Register(container *Container) error {
 		close(container.waitLock)
 	} else if !nomonitor {
 		container.allocateNetwork()
-		go container.monitor()
+		// hostConfig isn't needed here and can be nil
+		go container.monitor(nil)
 	}
 	return nil
 }