Adds:
- enum ProvisioningChange
- LinkProperties#compareProvisioning()
return a ProvisioningChange value describing the delta in
provisioning between two LinkProperties objects
- LinkProperties#removeDnsServer()
- make "@hide public" isIPv4Provisioned() and isIPv6Provisioned()
Bug: 18581716
Change-Id: I3df90b2b89617f693346f2dbe72e77c88ce91ffd