notifications: pass back notification id after creation

Signed-off-by: Simon Busch <morphis@gravedo.de>
Use new service name for notifications and add close method

Signed-off-by: Simon Busch <morphis@gravedo.de>
Rework taking screenshots to fit new API

Signed-off-by: Simon Busch <morphis@gravedo.de>
Merge pull request #101 from webOS-ports/morphis/notifications

Morphis/notifications