Added on change action

• Thanks to @hunter-koppen for adding attribute on change action: #3

Updated NPM packages

• @mendix/pluggable-widgets-tools from "10.5.0" to "10.15.0"
• ace-builds from "1.35.0" to "1.36.2"
• classnames from "2.2.6" to "2.5.1"

Minor change

• Added deboundChangePeriod property

Initial release

Initial release