Removing duplication + a lot of changes

Hi,
this is quite a lot of changes. The fact that youtube and vimeo videos where the same Video Object behaving differently was smelly and introducing a lot of duplication.
Both youtube and vimeo are now have there own class.

We can still create a new video with the command `Conred::Video.new`

I think the code is cleaner and it would now be easier to add a new "type" of video.

Tell me what you think about it.