Fix for Lint warnings

* Adding comments for missing exported functions

Change-Id: I40c5861a5c076b654e5a3fc660c3c9c6d7b80c8f
Relates-To: #148

pkg/container/container_docker.go

@@ -206,6 +206,7 @@ func (c *DockerContainer) getImageID(url string) (string, error) {
 	return img[0].ID, nil
 }
 
+// GetID returns ID of the container
 func (c *DockerContainer) GetID() string {
 	return c.id
 }