Node on change handler & Version Bump

We only have a node click callback which gets executed when you click the node but not when you select/deselect checkbox.

This pull request adds a node on change handler which gets executed whenever a node is selected/deselected.

Also has version bump changes. Right now when I install this repository using bower I don't get the code related to the click handler since that commit hasn't been tagged.

In case you merge this pull request, please create a tag so that we get the latest build when installed via bower.