Add a nicer loading indicator.

src/LoadingIndicator.tsx

@@ -0,0 +1,8 @@
+import * as React from 'react';
+import CircularProgress from 'material-ui/CircularProgress';
+
+export default (props: any) => {
+  return (
+    <CircularProgress size={60} thickness={7} />
+  );
+};