Set window title for Launcher, Launcher Popup and Background to be ""

Sets the window titles of those three apps to "" as per orbital!40 (comment 25551), and when combined with orbital!40 (merged) will accomplish the purpose of the issue orbital#47 (closed) which is to filter out those windows (that don't make much sense to switch to) from the window switched.

P.S: The window switched still has a number of issues, but those will be addressed separately.