Move fake_network opt to nova.network.manager

This is only used in the network.manager and linux_net.

blueprint: scope-config-opts
Change-Id: Id39a6a8427b293d1d9f9f22be12357b206910d72
Add ping to conductor

This adds a ping() method to conductor, which takes a single
argument and returns it back to the caller. It also returns
the name of the current service, which is always 'conductor' in
this case. I did this because I think that a generic ping method
should do this in order to facilitate blind or broadcast pings.

Related to bp/no-db-compute-manager

Change-Id: I83105060945fa6a793d884c9e06ff154bc98e715
Merge "Move fake_network opt to nova.network.manager"
Merge "Add ping to conductor"