force false value of an unselected single valued checkbox instead of null
Merge pull request #108 from bmeurant/master

update populate model checkbox management for single valued checkoxes
Fix issues related to require and QUnit.

* Update QUnit to the last version
* Use the new QUnit phantom runner
* Temporarily downgrade to require-2.0.6 for tests only because of an
  issue with phantom, see jrburke/requirejs#618
* Disable QUnit autostart to manually start the tests once every test
  files required

History tests have temporarily been removed from the suite: to be
refactored.