Moving over changes to develop to 2.7.  Changes include

- Achievements Bugfixing
- Essay Answer Upgrades (backtick formatting)
- math4 tabber integration
Fixed a bug where jquery was being loaded and clobbering bootstrap
Hows this for lots of commits
Merge pull request #43 from goehle/upgraded2.7

Upgraded2.7
Merge branch 'release/2.7' of https://github.com/openwebwork/webwork2 into release/2.7

This has bugfixes that Goeff added to math4 theme
also uses bootstrap tabs.
left align footer message