This takes the NotificationManager and splits it into multiple
compile units based on the backend that is available.
The 'dbus' was the only one available so far (which serves
kde/gnome desktops) and this is moved to its own file.
This adds android support as well, but so far only for block
notifications (when a new block is mined).
On Android an app can ship with (static) shortcuts. We use this feature
to allow the user to create a new icon which still starts Flowee Pay,
but it instantly opens the payment screen on the QR scanner.
Some phones have rather extreme rounded edges around the image,
which cut off too much of the logo to be comfortable.
This makes the logo a bit smaller with more blue background that
is Ok to be cut off.
tomFlowee