upgrade jquery ui to 1.10.4
do not enable jquery ui tabs that aren't there

(the current custom build does not include them)
reorder cells by dragging and dropping

using jquery ui "sortables"
closes #284

pretty elegant... the only thing that was messy was providing a
way to skip firing events from notebook model events, since we don't
want the reactions that create and destroy visual elements (cell views)
and need a higher-level "moved" event over "remove" and "add"

jquery.ui is pretty freaking amazing
artifacts
Merge branch 'feature/reorder-cells' into develop

Conflicts:
	htdocs/js/rcloud_bundle.min.js
Merge branch 'develop' of https://github.com/att/rcloud into develop

Conflicts:
	htdocs/js/rcloud_bundle.min.js