Revert "Do not show the titlebar when eog is maximized."

This reverts commit c93aa0b9.
As the menubar comes pretty close to the top of the screen,
there is apperently the possibility to accidentially trigger
gnome-shell's activities menu. Revisit this for the next development
cycle when all the dependencies are stable enough.

https://bugzilla.gnome.org/show_bug.cgi?id=671643