Add support for v0.11 GRPC services

This also refactors the client GRPC wrapper to dynamically load the
request objects.
All GRPC generated client files now live under lib/grpc_services

lib/grpc_services/watchtowerrpc/watchtower_services_pb.rb

@@ -0,0 +1,28 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# Source: watchtowerrpc/watchtower.proto for package 'watchtowerrpc'
+
+require 'grpc'
+require 'watchtowerrpc/watchtower_pb'
+
+module Watchtowerrpc
+  module Watchtower
+    # Watchtower is a service that grants access to the watchtower server
+    # functionality of the daemon.
+    class Service
+
+      include GRPC::GenericService
+
+      self.marshal_class_method = :encode
+      self.unmarshal_class_method = :decode
+      self.service_name = 'watchtowerrpc.Watchtower'
+
+      # lncli: tower info
+      # GetInfo returns general information concerning the companion watchtower
+      # including its public key and URIs where the server is currently
+      # listening for clients.
+      rpc :GetInfo, GetInfoRequest, GetInfoResponse
+    end
+
+    Stub = Service.rpc_stub_class
+  end
+end