Authentication and Simple Authorization

This release is among the last in the "legacy" branch that should honor the storage engines added before v1.0. Authentication through flyem-services is supported. After logging into flyem-services, you can call the /api/server/token to get a JWT that is optionally required for other HTTP requests via the Authorization header using the Bearer schema (see http://jwt.io/introduction). If the [auth] section in the configuration TOML is not set, no authentication and authorization is provided.