Refactor&cleanup on FieldGroug commit events

Also, fix & add tests
Merge branch '3.0' of github.com:henrikerola/scaladin into 3.0
Initial implementation of bootstrap listeners
code style fixes
Session init listener
fixed tests to pass
renamed property to getProperty
Renamed item to getItem
parent -> getParent
childrenAllowed ->  isChildrenAllowed
code style fixes
children -> getChildren
Moved CssLayout tests to their own file, renamed css -> getCss, code style fixes
Code style fixes
code style fixes
code style fixes
Info about Vaadin forums
code style fixes, ListenersSet (needs better name), ClickNotifier
Merge branch '3.0' of https://github.com/henrikerola/scaladin into 3.0
Moved Focusable trait inside Component