Merge pull request #469 from danjee/master

Added a spinner component
[spinner] Use spaces instead of tabs as all other classes in the project
[spinner] Issue #469 - Make 'initval' a String with default value ""
[spinner] Issue #469 - Make it possible to register only for the some of the possible event notifications
[checkboxx] Demo - use NotificationPanel instead of plain ComponentFeedbackPanel
[NotificationPanel] Fixes #470 - NotificationPanel should act as a
fenced feedback panel