Add Goclient to the repo, change the loader to use it.

cmd/dgraph/main.go

cmd/dgraph/main_test.go

cmd/dgraphloader/main.go

contrib/hooks/pre-push

goclient/.gitignore

goclient/client/client.go

goclient/client/client_test.go

goclient/client/value.go

loader/loader.go

query/graph/graphresponse.pb.go

query/graph/graphresponse.proto

rdf/parse.go

rdf/parse_test.go

types/conversion.go

worker/backup_test.go