Proto: Rename dgraph.badger.v2.pb to badgerpb2 (#1314)

This PR renames badger protobuf package from `dgraph.badger.v2.pb`
to `badgerpb2`. 
The `pb.pb.go` file has been regenerated using the `pb/gen.sh` script.

Author: Ibrahim Jarif

pb/gen.sh

@@ -5,3 +5,7 @@
 protos=${GOPATH-$HOME/go}/src/github.com/dgraph-io/badger/pb
 pushd $protos > /dev/null
 protoc --gofast_out=plugins=grpc:. -I=. pb.proto
+
+# Move pb.pb.go file to the correct directory. This is necessary because protoc
+# would generate the pb.pb.go file inside a different directory.
+mv $protos/github.com/dgraph-io/badger/v2/pb/pb.pb.go ./

pb/pb.pb.go

@@ -17,7 +17,7 @@
 // Use protos/gen.sh to generate .pb.go files.
 syntax = "proto3";
 
-package dgraph.badger.v2.pb;
+package badgerpb2;
 
 option go_package = "github.com/dgraph-io/badger/v2/pb";