filesystem: Fix top-level monitoring by adding add_monitor calls.
filesystem: Fix top-level monitoring by adding add_monitor calls.

https://bugzilla.gnome.org/show_bug.cgi?id=730841

MathieuDuponchelle/grilo-plugins,jasuarez/grilo-plugins,grilofw/grilo-plugins,vrutkovs/grilo-plugins,MathieuDuponchelle/grilo-plugins,MathieuDuponchelle/grilo-plugins,vrutkovs/grilo-plugins,MikePetullo/grilo-plugins,vrutkovs/grilo-plugins,MikePetullo/grilo-plugins,GNOME/grilo-plugins,GNOME/grilo-plugins,grilofw/grilo-plugins,vrutkovs/grilo-plugins,jasuarez/grilo-plugins,MikePetullo/grilo-plugins,MathieuDuponchelle/grilo-plugins