Extend jQuery object with form2json collection call.
The form2json method allows chaining.
Test event hooking.
submitFormAsJson call with callback.
Better tests.
Test event is hooked.
Dry and sanitize.

The submitFormAsJsonTest wrapper has named attributes.
The callback in the submitFormAsJsonTest wrapper has been changed
to use the now native callback option of Form2Json.submitFormAsJson.
Button click submit test.
Handle submit button clicks.