jQuery 1.9 compatibility + Grunt

This pull request changes the following:

- jQuery 1.7 and 1.9 compatibility,
- Grunt build infrastructure.

jQuery 1.9 compatibility
------------------------

jquerytools dev branch is mostly 1.9 compatible. I created a fork in the collective organization and backported some more changes from plone.app.jquerytools. This pull request is based on the ``dev`` branch of jquerytools. Also see:

- Our jquerytools fork: https://github.com/collective/jquerytools/tree/dev
- The jquerytools pull request: https://github.com/jquerytools/jquerytools/pull/1076

There are also important changes in ``overlayhelpers.js``:

- https://github.com/plone/plone.app.jquerytools/pull/8/files#diff-21

And the jQuery Form Plugin:

- Our jQuery Form Plugin fork: https://github.com/thet/form
- The jQuery Form Plugin pull request: https://github.com/malsup/form/pull/419


Grunt build infrastructure
--------------------------
The Grunt script can surely be improved, but it works quite well for my purposes at the moment. I'm using grunt-shell to do git checkouts of the forks I created.


Related Jenkins build
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http://jenkins.plone.org/job/plone-4.3-python-2.7/2352/

Benefit
---------
I needed these changes for Bootstrap 3 compatibility, which itself depends on jQuery 1.9+

@davisagli @smcmahon please have a look at these changes