1. Renamed GetResponse to Query in DGraph service.
2. Client now accepts the ip of the server as a flag instead of just the port.
3. Removed ToProtocolBuffer method, and added PreTraverse as a method for a Subgraph.
4. Renamed runServerForClient to runGrpcServer.

Client now gets back protocol buffer data and is able to parse it into protocol buffer Subgraph

1. Added subgraph.proto file which has the message structure.
2. Added ToProtocolBuffer method which converts a subgraph to protocol buffer.

Remove gql module's dependency on query. Make it the other way round. GraphQL query string, now gets converted into query.SubGraph as an additional step run via query.ToSubGraph.

Handle reading rdf data from files. Use underscores for uid and xid, keeping it in sync with internal usage. Output uids as hex.

Make list matrix work, yeah! This would serialize uids for the next query, which would then again return a matrix, so on and so forth.

BREAKING change: convert to JSON. Given we're not tracking uids for each query uid, this will cause problems for the result. So, have to re-structure stuff here.