Reverse lookup for aliases

[mrosecrance]

This PR addresses https://github.com/cloudfoundry/bosh-dns-release/issues/72

With a job aliases.json file that looks pseudo-ish like this: a: 123.group.vm (pretend this is the FQDNs) b: q-s0.group.vm (returns all vms in an instance group that are healty) c: *.group.vm (wildcard on instance group) d: .group.vm (vm1d would match vm1.group.vm) e: 123.group.vm, 234.group.vm (two FQDNs) f: 1.1.1.1

All of these aliases potentially could resolve to 1.1.1.1. This PR will change a reverse ip lookup on 1.1.1.1 from only returning the FQDNS to returning a, e and f as well. It will match on exact FQDNs's or ips in the alias values and ignore the others.

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/175584689

The labels on this github issue will be updated when the story is started.

[linux-foundation-easycla[bot]]

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