View count feature for vimeo and youtube videos added.

I have added a feature to obtain the view count of the youtube and the vimeo videos. The user can use this feature in many ways such as to embed a video only if the view count is greater than a certain number etc. if the video doesn't exist, nil is returned otherwise the number is returned as an integer. I have also added the Rspec tests for it.
Hey, can you please change this method name to view_count ?