Fixed zen and IPython themes for v7

OK, the `zen`, `zen-jinja` and the `zen-ipython` themes are fixed and working with v7.
I also update the css for the `ipython` and `ipython xkcd` themes.
All of them seems to work as expected... I also fixed some bugs, made the css compiled available, and now the themes are compatible with the new look of IPython 2.0 notebook!!!

BTW, I love `zen-ipython` :stuck_out_tongue_winking_eye: 

Regarding the reveal themes... I have not seeing anybody using it... they are time consuming in maintenance and not enough nice to keep them... so, I would vote to deprecating them... I can do it in this PR or another, just let me know your thoughts about that...