Initial work on using json-schema

Made schemas a part of a spec, figuring out how to enable extending
schemas and validating against runtime determined schemas.
Basic registry with flask, rethinkdb and GitHub auth. API only.
newline
checksum and links
token crud
Checkpoint.
Very ugly client. Very ugly flow. But working.
No error if not authenticated. Showing jsonref on app page.
checksum fix
Merge from jsonschema
newline
Extracted models
Validating models using schema. Partially.
whole schema for models
Referencing apps from pipeline schema
merge
Merge pull request #46 from rabix/feature/registry

Feature/registry