Introduce Color Label Filter widget. This widget show a list of color label...

Introduce Color Label Filter widget. This widget show a list of color label selectable (through check-box).
This widget will be used to perform Color Labels icon-view filter from statusbar.
A preview of this widget in action is given below:

http://www.flickr.com/photos/digikam/5431174228/sizes/o/in/photostream/

Note: On status bar, push button text is the count of color label checked.
For the moment this button is not displayed. Icon-view filtering by Color Label is not yet implemented.
CCBUGS: 152424