Merge branch 'release/2.7' of https://github.com/openwebwork/webwork2 into release/2.7. Fix conflicts caused by merging mathview.

 one line bug fix for scroll bars.
Reset PG_VERSION link
Correct perl error (using @ when $ should be used on an array)
Add switch for turning MathView on an off

Also moved the actual subroutine for printing the links to the mathview scripts to ContentGenerator.pm.  We may be adding jquery too many times -- not checking for this at the moment.
Merge branch 'mathview2' into release/2.7tmp
Use CGI calls to format script references
Add jquery_ui conditionally in the templates