make loading MathJax optional
remove part of link.css that hides all bootstrap tabs
Merge pull request #127 from oerpub/oer-paste-handler

Paste plugin, simpler than the aloha one.
Merge pull request #121 from oerpub/mathjax-optional

make loading MathJax optional
Merge pull request #126 from oerpub/show-tabs

remove part of link.css that hides all bootstrap tabs
Merge remote-tracking branch 'origin/master' into undoredo
Add some smartContentChange triggers in places.

This way, dragging things around and dropping them in place generates
a content-change event.
Determine xpath of containing node, not text() node itself.
Collect mutations, on smart-content-change, figure out top modified item and store a copy.