Schema-related API changes
changes taken from !68 (closed) MR. several fixes applied against original MR:
- getSchema method cannot return 409 response, this is a copy/paste error, most probably. 409 response section moved to PUT operation
- getLatestSchemas method - renamed to getLatestSchema as it returns only one schema (String)
- getLatestSchemas method - type parameter made optional, otherwise the second parameter makes no sense