feat(graphite): added stddevSeries func def, closes #4782

public/app/plugins/datasource/graphite/gfunc.js

@@ -80,6 +80,13 @@ function (_, $) {
     category: categories.Calculate,
   });
 
+  addFuncDef({
+    name: 'stddevSeries',
+    params: optionalSeriesRefArgs,
+    defaultParams: [''],
+    category: categories.Calculate,
+  });
+
   addFuncDef({
     name: 'divideSeries',
     params: optionalSeriesRefArgs,