tie in 'forgot password' workflow in CAS LMS

Add "high level source" editing capability for problems & html; provides latex2edx I/F

tweaked import text; added check for .tar.gz

Tweaks to the unit location pane

added white background to codemirror

removed section dates; fixed fly in dragging

Fix/cdodge/signup tweeks

polished import progress bar

changed save unit alerts to toast

polished new course form

don't show courses/create new course if account has not been activated. ...

don't show courses/create new course if account has not been activated. Also better error messaging on failed logins. Also redirect to index after signup.

fix preview draft link. We need to generate the link target url directly...

fix preview draft link. We need to generate the link target url directly rather than using jump_to. I think jump_to is not properly finding the draft objects and needs more investigation

fixed x_module.py to only load *.yaml files as templates
TODO: Note that bad templates cause the CMS not to load; it should throw
exceptions instead of dying.

always hide the pages button. We don't want it appearing in case someone...

when calling jump_to when location=<id-of-sequential> then Position is b...