VimeoVideo

A quick and simple addition to IPython/lib/display.py to make it possible to display Vimeo video in a notebook.

Factored most of the code out of YouTubeVideo into VideoIframe making it trivial to create new class for video service offering embedded  video in the form of an iframe.

(needed it for a SyPy talk in May entitled PANDAS: Python has R envy in which I want to embed Wes' 10 minutes to Pandas video)