merge reveal templates into one

there was very fine-grained subclassing in reveal_internals,
which I don't think was beneficial.
update components

to latest in ipython-components

closes #4765
we don't bundle lessc anymore, remove its vestiges
marked now adds ids to header tags
reorder slide branch per review
Merge pull request #4796 from minrk/update-components

update components

closes #4765
Merge pull request #4795 from minrk/single-reveal-template

merge reveal templates
Added widget output area
Add widget subarea style
Added dependencies to page.html template and added widget.js to notebook.html
Added widget.js
Added widget.py
Added widjet.js
Other commit actually added notebook.js changes
Fixed widget.js and notebook.js so IPython.notebook.widget_manager is created.
Fixing infinite recursion.
Added apply method to base model.
Allows model to propogate changes to all views except
for the one specified.
Added display hook logic to handle widgets
Basic display logic
s/show/_repr_...
Added code to display Javascript in frontend.
Moved widget.js into widget code directory
Added utility function to send all the javascript
in the current directory to the frontend.