Add alternative json mimetype

I think it may be useful to decode JSON served under JSON API mimetype.
http://jsonapi.org/
Search Content-Type header with regexp
Merge pull request #85 from willianpts/master

Parse additional json content-type: application/vnd.api+json
update endpoint, add client_id

(we update the API endpoint, and will be requiring client_id's starting Dec1)

Thanks!
-Eric
Merge pull request #87 from case/patch-2

Update Domainr endpoint
Add required field client_id