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).
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