Bugfix : https://jira.esrf.fr/browse/ACU-1153

Improved what had been done and integrated in !14 (merged) The checkbox can be created with a 'need confirmation' option : it will show a pop up window to user asking if the she's really sure to change the selected status. This version improves the graphic feedback to user : the one integrated in the commented merge request was quite confusing;the checkbox displayed the 'future' status when the warning pop up was displayed. if user decided to cancel the action, the checkbox status was reverted. Now the selection change is blocked in the GUI until the user accepts the change Two pure graphical widgets have been also added to fr.esrf.tangoatk.widget.util package : SwitchButton and ATKColorChooserButton,