Refactor&cleanup on FieldGroug commit events

Also, fix & add tests
Merge branch '3.0' of github.com:henrikerola/scaladin into 3.0
Merge branch '3.0' of github.com:henrikerola/scaladin into 3.0
Upgrade to 7.1, add access to UI
Merge branch '3.0' of github.com:henrikerola/scaladin into 3.0

Conflicts:
	addon/src/main/scala/vaadin/scala/FieldGroup.scala
	project/Build.scala