Fixed race condition in agent init
Fixed race condition in agent init

There is a possible race condition when agent is starting - events
from Neutron tries to get self.network_map in handler, but this
list is not yet initialized

Mirantis/vmware-dvs,ekosareva/vmware-dvs,ekosareva/vmware-dvs,Mirantis/vmware-dvs,VTabolin/vmware-dvs