Settings: Show heads up at the bottom of the screen (2/2)

Due of user requests and indeed especially on hw key devices for a better
workflow we add an option to show heads up notifications on the bottom instead
of the top.
Animation we leave as is due that if it slide from the bottom into the screen it happens
to often that the user accidentaly interacts with it. If it comes from the top of the
container we add, the user has enough time to realize it. Sometimes a ms can make a big difference.
Change-Id: Ieab601df1dc4fa5350fe4b9e4952198eb8e2d788
Merge "Settings: Show heads up at the bottom of the screen (2/2)" into pac-4.4