Fix idempotency for neutron_floatingip_pool

1) Change insync method to return true if we have at least
   specified amount of floating ip addresses

2) Change tenant name for floating ips to 'services'
   or IPs will be created each time deployment is run

Change-Id: I3cf54e2326b29421f4f7c8c8559d773886e23189
Closes-bug: #1395739
Merge "Fix idempotency for neutron_floatingip_pool" into stable/5.1