Import the extension, index.html and app.js files

As discussed here github.com/GoogleChrome/webrtc/pull/85 with @juberti.

These are only the essential files from my example app.

In order to run the example, one needs to serve it over https.  For
convenience I included a small ruby script in the [original
repo](https://github.com/wpp/ScreenStream) but I'm not sure how you feel
about that.

What is also missing is the README any thoughts on that? Should the
documentation only live in the `.js` files? (I would need to add some
then.)
Updates manifest urls for github pages (@jiayliu feedback)
adding maxplaybackrate as a codec parameter
making names shorter
Kind of working test.
Now also checking video finish.
Added checking of video tag.
refined comments, stopped stream etc
replace reportWarning with reportError
some comments salt and pepper and tobasco
rename files, no tobasco this time.
Merged