The document gallery has been pretty much unmaintained for a year
now and the only backends we have are for tracker (ie. the N9),
the deprecated jsondb client API and the simulator. it doesn't
work anywhere else currently.

Change-Id: I5c12e23be7ed8862e891e996fbd6191e79f4fdef
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>
Reviewed-by: Marius Storm-Olsen <marius.storm-olsen@nokia.com>