unit-tested proper vimeo uri request

Hi,
I have noticed that your test cases were not covering the VimeoStrategy#api_uri so I wrote a test for that.
Also, you might want to have a look at the naming of your test methods. Some don't really communicate the intent, e.g.; "should be true if response is 200" could be more like "when a video exists response is  200" (with the first part in the describe)