Set record.message to ensure msg is shown in the Stackdriver UI

Author: Binarytales

lib/bunyan-stackdriver.js

@@ -93,6 +93,10 @@ BunyanStackDriver.prototype._write = function write(record, encoding, callback)
   record = destroyCircular(record);
   strictJSON(record);
 
+  if (!record.message) {
+    record.message = record.msg;
+  }
+
   var metadata = {
     resource: this.resource,
     timestamp: timestamp,