Keep remote volume monitor proxies alive forever
Keep remote volume monitor proxies alive forever

Once constructed, it's a) more efficient; and b) simplifies the code;
if we keep the proxy for a remote volume monitor process around.

More importantly, this change sidesteps some thorny bugs in the
current implementation where the remote volume monitor proxy has been
disposed but not yet finalized - for some volume monitors, this can
happen not only pathological situations but also when running
e.g. gvfs-mount(1) to mount a volume.

https://bugzilla.gnome.org/show_bug.cgi?id=660295

Signed-off-by: David Zeuthen <16a4bae6a7afea1fdd75baca6404fe68f285db96@redhat.com>

halfline/gvfs,cpatulea/gvfs,xkahn/gvfs-cmis,philipl/gvfs,gicmo/gvfs,halfline/gvfs,gicmo/gvfs,philipl/gvfs,halfline/gvfs,cpatulea/gvfs,philipl/gvfs,xkahn/gvfs-cmis,xkahn/gvfs-cmis,gicmo/gvfs,xkahn/gvfs-cmis,gicmo/gvfs