Add RecordsService
Add ContactsService
Add NameServersService
Cleanup specs
Add ServicesService
Add TemplateServices
Add UsersService
Add TemplatesService records
Ability to apply a template
Add DomainsService
Add DomainsService auto renewal
Add domain check
Add domain registration, transfer, renewal
Add CertificatesService
Extract custom extra
User should be able to pass a custom CSR
:body is now the default payload in options

You can pass :header and :query and they will be properly extracted and
merged for the HTTP client.
Test request error case
Update the docs to reflect the new interface
Merge pull request #55 from aetrion/services

Convert the Client interface into a "proxy"-based design