Fix indexjs current style (motdotla#268)

* Fix handler to current style

* Fix to unify console.log argument to `lib/main.js` style

Author: abetomo

index.js

@@ -1,9 +1,9 @@
 // For development/testing purposes
-exports.handler = function( event, context ) {
-  console.log( "Running index.handler" );
-  console.log( "==================================");
-  console.log( "event", event );
-  console.log( "==================================");
-  console.log( "Stopping index.handler" );
-  context.done( );
+exports.handler = function(event, context, callback) {
+  console.log('Running index.handler');
+  console.log('==================================');
+  console.log('event', event);
+  console.log('==================================');
+  console.log('Stopping index.handler');
+  callback(null);
 };