RMIB: expose full node path; improve restartability
A single function may be used to handle the implementation of more
than one node. In some cases, the behavior of that function may
depend on the path name used to reach the node. Therefore, provide
the full path name as part of the call information.
As a result, RMIB has to save the paths for each of its remote MIB
mount points. That in turn also allows it to autonomously remount its
mount points after a MIB service restart, thus bringing us a step
closer to proper recovery after a MIB crash without requiring the
service using RMIB to perform explicit steps. As before, the missing
ingredient is actual notification of MIB service restarts, and proper
support for *that* will likely require changes to the DS service.