DataFrame_repr_html changes according to #772 discussion.
cc @ellisonbg

Implemented changes as discussed in #772.
Not so crazy on the scrollable div. For now i left the div max sizes as they were, could use suggestion on _good_ values.

I don't use the notebook often, what i noticed just now is that in combination with the IPython notebook `get_terminal_size()` returns the size of the terminal where the notebook was launched, not the size of the notebook display area. Don't know if there is a way to get the notebook size.

I'm pretty sure we haven't implemented any way to get the notebook size - in any case, the window can always be resized later, or the notebook could be reopened on another screen.
 @lodagro can you add an option to set_printoptions in the print configuration that will disable the HTML output (and any other notebook-enhanced reprs, eventually)? It may be as simple as raising an exception
 By default notebook will use _html repr_, but you can do `set_printoptions(notebook_html_repr=False)` to revert back to _plain text repr_ in the notebook (available in this pull request). 
 Oh cool, you are way ahead of me. thanks
