Rate media on new thread

When the user presses the rate button, it does the rate request in a new thread, closing the dialog in the process.
Its just to make things a little more responsive and let the user know that the button has been pushed and the script is doing something.
With the current implimentation it can take a few seconds between when the user has pushed the rate button and the dialog closing.

EDIT: no longer uses new thread, but achieves the same result.