message: fix mismatch
diff: @@ -110,7 +110,7 @@ function Botkit(configuration) {
  };
  botkit.categorize = function(obot, omessage) {
  - message._pipeline.stage = 'categorize';
  + omessage._pipeline.stage = 'categorize';
  botkit.middleware.categorize.run(obot, omessage, function(err, bot, message) {
  if (err) {
  console.error('An error occured in the categorize middleware: ', err);
  @@ -124,7 +124,7 @@ function Botkit(configuration) {
  };
  botkit.receiveMessage = function(obot, omessage) {
  - message._pipeline.stage = 'receive';
  + omessage._pipeline.stage = 'receive';
  botkit.middleware.receive.run(obot, omessage, function(err, bot, message) {
  if (err) {
  // log the error to console, so people recognize it
  