Implemented the dialog to ask for confirmation when the user ask to delete a card

No keyboard shortcut implemented, yet

frontend/delta/properties/delta.properties.json

@@ -137,6 +137,7 @@
 		"Clipperz/PM/UI/Components/Checkbox.js",
 		"Clipperz/PM/UI/Components/CardToolbar.js",
 		"Clipperz/PM/UI/Components/MessageBox.js",
+		"Clipperz/PM/UI/Components/DialogBox.js",
 		"Clipperz/PM/UI/Components/Selections.js",
 		"Clipperz/PM/UI/Components/TagIndexItem.js",