Fixed the case where "required" rule is not needed but a callback must still be run. Previously the callback was ignored if "required" was not present.
Merge pull request #50 from TimBenjamin/master

Fixed issue #49
[fixes #48] Fixed the issue where the global event variable was being overwritten in IE.
Updated version number to 1.2.2
Merge branch 'master' into gh-pages
Updated release notes for 1.2.2.