First working version of automated execution of notebooks in example folder.

Very WIP... I will work more on this in the next days...

Edit: No longer a WIP.
So you want to wait 15 seconds for every notebook example? I know where this comes from and you will end up increasing this limit over and over again (see `--timeout`). I waited with testing notebooks after I figure out how to setup "finish" event notification from ipython notebook and bokeh. Otherwise, this will work and fail from time to time, but this is how things work now anyway, so it's not that big deal, thought 23 notebook examples will add extra 5 minutes of testing (waiting) time per configuration.