Merge changes from 'instructors-guide' branch to book/*.html.
Fixing tabs
Merge branch 'master' of github.com:swcarpentry/website
Merge branch 'master' of github.com:swcarpentry/website
Changing menu item title
Moving image
1. Fixing formatting of bootcamps/2013-02-amos.html.
2. Adding new "What We Do" page (a revamp of the old 90-second pitch).
Merge pull request #234 from gvwilson/master

Fixes to web site