Move Notifier into its own file
diff --git a/src/ruby/lib/grpc.rb b/src/ruby/lib/grpc.rb
index b0f6803..80b5743 100644
--- a/src/ruby/lib/grpc.rb
+++ b/src/ruby/lib/grpc.rb
@@ -30,6 +30,7 @@
 require 'grpc/errors'
 require 'grpc/grpc'
 require 'grpc/logconfig'
+require 'grpc/notifier'
 require 'grpc/version'
 require 'grpc/core/time_consts'
 require 'grpc/generic/active_call'