Added className to Loader

public/loading/Loader.jsx

@@ -25,7 +25,7 @@ import React from 'react';
 
 export default function(props) {
   return (
-    <span className="o-loader">
+    <span className={"o-loader"+(props.className?" "+props.className:"")}>
       <svg width="38" height="38" viewBox="0 0 38 38" xmlns="http://www.w3.org/2000/svg" className="o-loader__image">
         <g fill="none" fillRule="evenodd">
           <g transform="translate(1 1)" strokeWidth="2">