Array

Hey. I wanted to patch commit https://github.com/vacationlabs/jsonform/commit/2ccf9f6740afffaea87871a3514e3425495f399d into jsonform as it was causing `onChange` events to not fire for `checkboxes`.

Didn't find any working branches so I am creating a PR with the `array` branch. Let me know if I need to do something else to get this commit onto master.

Ashwin