Fixed the IMDb plugin slightly

The IMDb api seems to have moved to omdbapi.com so I changed the
url (seems like the old url still works for now though).

I also fixed so the plugin gets the rating and id properly again,
since these seem to have changed at some point.

The api is still shit though and half of the requests times out.
Maybe it's possible to get something better working using IMDbs
"secret" api?