Delete include array if empty

lib/model.js

@@ -1713,6 +1713,9 @@ module.exports = (function() {
     // if include is not an array, wrap in an array
     if (!Array.isArray(options.include)) {
       options.include = [options.include];
+    } else if (!options.include.length) {
+      delete options.include;
+      return;
     }
 
     // convert all included elements to { Model: Model } form