Exclude provider subnets from overlapping CIDR validation
Exclude provider subnets from overlapping CIDR validation

Including the provider subnets as part of the validation caused
a BadRequest as their cidrs span the entire IP space. This would
prevent quark administrators creating any new subnets under provider
networks.

JIRA:NCP-1746

lmaycotte/quark,alanquillin/quark,asadoughi/quark,roaet/quark,Cerberus98/quark,asadoughi/quark,lmaycotte/quark,roaet/quark,rackerlabs/quark,rackerlabs/quark,alanquillin/quark,Cerberus98/quark