A couple of bug-fixes and a fail over capability for the partitioned client

The first couple of commits are pure bug-fixes; I think they should be applied to the main project.

I also added a fail over capability to the partitioned load balancer client and a capability to work with non monotonically increasing partition identifiers (this is still being tested).

Protocol buffers was brought to a more recent version, 2.5.0 and the protocol files were re-generated.