Allow CNAME creates

[rebstar6]

The following command should work to create a CNAME (if that zone id existed):
vinyldns record-set-create --zone-id d825a806-49ee-4c97-b010-daaed19b92c3 --record-set-name some-cname --record-set-type CNAME --record-set-ttl 123 --record-set-data test.com

Right now, I get the following response:

Request URL:
<omitted>
Request Method:
POST
Request body:
{"zoneId":"d825a806-49ee-4c97-b010-daaed19b92c3","name":"testingCLIcname","type":"CNAME","ttl":123,"account":"","records":[{"address":"test.com"}]}
Response code: 
400
Response body:
{"errors":["Missing CNAME.cname"]}```

This should be a small fix. per https://www.vinyldns.io/api/recordset-model#record-data, the record data for a CNAME is cname, but it looks as though the CLI is sending address, which is the data for an A or AAAA. Should just need to update https://github.com/vinyldns/vinyldns-cli/blob/master/vinyldns.go#L659 to not hardcode Address as that field name.