If 'name' field of request ends in dot, you get a 500

[cjellick]

On posting new records, if you have an entry that looks like this:

{
    "name": "test.",
    "type": "TXT",
    "values": ["xyz"]
}

We will construct the FQDN to send to route53 as test..foo.on-acorn.io. That double dot will cause route53 to blow up with:

    "msg": "failed to upsert route53 record _acme-challenge..zpab5z.dev.on-acorn.io with error InvalidChangeBatch: [FATAL problem: DomainLabelEmpty (Domain label is empty) encountered with '_acme-challenge..zpab5z.dev.on-acorn.io']\n\tstatus code: 400, request id: a6f2a8e6-c024-4010-8a90-24a75be269e4"

We should handle that more gracefully through validation.