Error message misspelling.

Fixing error message misspelling.

lib/connection.js

@@ -423,7 +423,7 @@ Connection.prototype.parseR = function(buffer, length) {
       return msg;
     }
   }
-  throw new Error("Unknown authenticatinOk message type" + util.inspect(msg));
+  throw new Error("Unknown authenticationOk message type" + util.inspect(msg));
 };
 
 Connection.prototype.parseS = function(buffer, length) {