implement the Service type

[sanchit1276]

trafficstars

What would you like to be added: Implement the Service type: type Service { name: String! # unique name for the service version: String! # any string schema: String! # the full schema for the service }

Why is this needed: so that Graphjin can be federated by Bramble and such

[dosco]

Can be done and should be fairly easy. Look at introspec.go