feat(loadingView): add setContent method

Author: ajoslin

js/views/loadingView.js

@@ -45,6 +45,11 @@
       window.clearTimeout(this._showDelayTimeout);
 
       this.el.classList.remove('active');
+    },
+    setContent: function(html) {
+      if (this._loadingBox) {
+        this._loadingBox.innerHTML = html || '';
+      }
     }
   });