Allows the json marshaller to be passed json marshal options (#4252)

diff --git a/ruby/lib/google/protobuf.rb b/ruby/lib/google/protobuf.rb
index 9b8d823..4a805e8 100644
--- a/ruby/lib/google/protobuf.rb
+++ b/ruby/lib/google/protobuf.rb
@@ -60,8 +60,8 @@
       msg.to_proto
     end
 
-    def self.encode_json(msg)
-      msg.to_json
+    def self.encode_json(msg, options = {})
+      msg.to_json(options)
     end
 
     def self.decode(klass, proto)