Clean up header bar
Maybe it could be worth to discuss, if
"GtkMenuButton" id="ring_menu"> could be removed from the header bar.
Affects account settings view as well. #791 (closed)
"Quit" functionallity is already handled by the window decoration ("x"). The "About" could be moved to Settings here.
For me this seems to be related to #808 as well.
What do yo think?