Move the file rule from the existing permissive system bus abstraction
into a new strict system bus abstraction.
The strict abstraction only allows for calling the Hello, AddMatch,
RemoveMatch, GetNameOwner, NameHasOwner, and StartServiceByName methods
that are exported by the D-Bus daemon.
The permissive abstraction reuses the strict abstraction and then allows
all communications on the system bus.
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: John Johansen <john.johansen@canonical.com>
