Add transient hint to notifications
Add transient hint to notifications

On gnome-shell, notifications are persistent by default, where the
user needs to clear the notification explicitly. So we add a transient
hint such that the notification doesn't stay in the notification area
indefinitely.

catkin/catkin_tools,scpeters/catkin_tools,catkin/catkin_tools,scpeters/catkin_tools,jbohren-forks/catkin_tools,k-okada/catkin_tools,k-okada/catkin_tools,iwanders/catkin_tools,jbohren-forks/catkin_tools,rhaschke/catkin_tools,iwanders/catkin_tools,jbohren-forks/catkin_tools,wjwwood/catkin_tools,pjreed/catkin_tools,wkentaro/catkin_tools,scpeters/catkin_tools,davetcoleman/catkin_tools,rhaschke/catkin_tools,rhaschke/catkin_tools,scpeters/catkin_tools,wkentaro/catkin_tools,catkin/catkin_tools,pjreed/catkin_tools,catkin/catkin_tools,iwanders/catkin_tools,wjwwood/catkin_tools,iwanders/catkin_tools