Merge pull request #51 from goehle/upgraded2.7

Fixed a bug where some tabber tabs were not being changed to twiter tabs...
Missed a conflict on merge
Fixed mistake!
Added a message when you dont have items.  (Small change)
Reorganize action buttons for PGeditor.

New labels:  View Update newVersion Appaend Revert
It is important that the label titles have no spaces in order for tabber to work properly
Still need to decide about opening in a new window, and default choices for that.
Some other rewording was also done -- hope it helps.
Forgot to include new achievement evaluators
Merge branch 'release/2.7' of https://github.com/openwebwork/webwork2 into release/2.7
change permissions on readme
Fix addresses for javascripts
Final? changes to addresses for javascript in SetMaker
Increase height of input tex blanks.

There was minimal spacing in chrome, but the letters were actually cutoff below in firefox.
Override height specification (made in bootstrap.css) by setting it to 'auto'.
Add output HTMLorMML  configuration for MathJax.

Adds MML output for use with MathReader accessibility
.
Changed the URL to the Bugs button to the new repository.
Protect against undefined string
Update mathjax
protect agains certain answer information not being defined.

uses // operator
Fixed issue #4, the visibility and reduced scoring not set on creating new sets.
Fixed issue #1 (and #8 a duplicate).  Rewrote the importer to use backbone.stickit.
Fixed issue #6
Fixed issue #7 at least with the width of the pulldown menus.