Switched 'equals()' to 'equal()' per new QUnit API
Moved clearing of mockjax requests into global teardown function
Separated some tests to be more atomic
Added a test for PUT (should resolve #70)
Added test for proper headers returned in response xhr object
Added failing test for missing third arg in success callback
Fixed header test to not break and stop all later tests
Merge pull request #153 from appendto/test-updates

Test updates