Release v1.1.2
Should empty errors array when calling clear.
Switch to using grunt-mocha-test.

Grunt-mocha-test has a few extra things that are useful
such as handling uncaught exceptions.
Use Chai instead of vanilla Node assert.

Chai gives much better assertion error information
on fails. Due to this I've removed the assertion
error messages since Chai already has good ones.

Closes #28.