siteSetup contains more properties than is needed for createSite operation

[daveaglick]

The createSite operation in the Open API specification uses the siteSetup definition for the body but that object appears to contain many more properties than are relevant for the operation. The API docs only mention name, custom_domain, password, force_ssl, processing_settings (see #47), and repo. Wondering if a new object definition should be created and referenced for the createSite operation?