[nailgun] Primary node roles information not saved

[Alexander Kislitsky]

After primary node selected (for controller or node) in serializer we just send information into orchestrator.
As result we have no information about which node is primary.

[Dima Shulyak (dshulyak)]

Nailgun should not store primary role assignment, cause it is dynamic

[Dima Shulyak (dshulyak)]

Sorry, my bad, looks like we will need to store it anyway, cause it affects adding of additional controllers, and i see no other way to resolve that issue.