Neutron Error Type constants and minor behaviors updates

- Updating common behaviors method wait_for_status param
  changing poll_rate for poll_interval
- Adding NeutronErrorTypes constants
- Minor update on behaviors clean up methods for better
  error handling
- Adding subnets behaviors get_ip, get_ips, get_host_routes
  and format_dns_nameservers helper methods
- Adding subnet quotas config properties

Change-Id: I85e38f0c651bb839601a33a1facd5ea6da819d87
Merge "Neutron Error Type constants and minor behaviors updates"