groupon/assertive — pull request #6 by johan (2014-01-12 07:30:26+00:00)
Title: Implemented hasType and notHasType

Based on @dbushong's implementation in #2, integrating my feedback for that branch, and mergeable with current master. Error messages for the negative assertions also fixed, and I added `Date`, `NaN`, `null` and `undefined` "types" too besides those in David's original branch.