Major refactor of modules and associated files

Removed submodules from the repo:  they cause problems, they clutter the _static directory with unnecessary files, Generally they are harder to use than they should be and require and extra step when setting up and building a repository.
update to latest skulpt
update conf.py files for no submodules
use new location for js/css files used by extensions
Add README(s) with some directions about css and js files
Update to latest pytutor.js
Update conf.py to use the latest locations for third party modules (skulpt, OPT, and js-parsons)
proof of concept for diff viewer

Conflicts:
	controllers/admin.py
Merge pull request #446 from presnick/master

Don't allow saving of programs that are part of assignments with deadlin...
add unit to CM resizing CSS (#70)
Merge pull request #449 from isaacdontjelindell/issue-448

Add missing CSS unit (#448)
update skulpt references
Get rid of the ugly para symbols at the end of each line.
formatting, plus add error messages to the right of the code.
remove semi colon at end of para
parse and add pylint output to the coach_hints table.
progress on getting basic lint functionality integrated into the coach
Refactor navigation through diffs
refactor so that this can be used either in bulk or by ajax.py when one new change is made.
run lint after each save.