Introduction slides + events slides +add setup and tearDown methods + fix some bugs

Manolo, I added few slides for the introduction and the event part : still a WIP.

I added also the possibility to define for each slide : 
- setup method : it is called first when we click on the play button. The idea is to run some code to initialze the demo without showing this code in the slide.
- tearDown method : it is called when the slide is being hidden. Allows to clean stuffs after the demo.