Python client: check if universe field is present when deserializing a Port
Python client: check if universe field is present when deserializing a Port

Right now, there is no way to distinguish a Port bound to universe 0
from a Port not bound to any unverse (its universe field will also be
0). This is because protobuf returns 0 by default if you ask for an
optional field that happens not to be present.

With this patch, an unbound Port will have universe=None.

ld3300/ola,nightrune/ola,ld3300/ola,nightrune/ola,nightrune/ola,ld3300/ola,ld3300/ola,ld3300/ola,nightrune/ola,ld3300/ola,nightrune/ola,ld3300/ola,nightrune/ola,nightrune/ola