Add in tests for JSON Schemas being produced

[shimks]

• JSON Schemas produced by repository-json-schema should be validated against this meta-schema (used to validate the schema itself): http://json-schema.org/schema. More information here: http://json-schema.org/specification.html#meta-schemas.

Acceptance Criteria

• write tests for types of JSON Schema in repository-json-schema
• validate JSON Schemas produced in the tests of repository-json-schema with a JSON-Schema-validating-JSON Schema

[virkt25]

A list of packages we can use for validation:
http://json-schema.org/implementations.html#validator-javascript

[raymondfeng]

https://github.com/epoberezkin/ajv

[rahulrkr08]

https://github.com/hapijs/joi ??