Update boilerplate to only use gramps for delegation

[kbrandwijk]

Right now, the gramps schema is used as main schema for the server. This is not according to best practices. This boilerplate should be updated to include a public schema, and use the gramps datasource for delegation only. This can be done after the graphql-binding PR is merged, so a binding can be created based on the exposed GraphQLSchema from gramps().