proof of concept for diff viewer

Conflicts:
	controllers/admin.py
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.
Add pylint as a requirement
Add blocks to layout to make it easier to customize for iframes
add sid and divid information to template.
exclude the superflous parens warning.
remove prints
fix path to rcfile, remove extra prints
Add first and last, prepare for using in iframe
Merge branch 'diffviewer'
Add show in codelens as an option to activecode
More interesting first example