Move ui-identicon -> react-identicon (#165)

* Move ui-identicon -> react-identicon

* ui-identicon import fix

* Update README package links

* Update doc sidebar links

* Adjust react-qr signatures, CHANGELOG

packages/react-identicon/src/icons/Empty.tsx

@@ -0,0 +1,26 @@
+// Copyright 2017-2019 @polkadot/react-identicon authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import { Props } from '../types';
+
+import React from 'react';
+
+export default class Empty extends React.PureComponent<Props> {
+  public render (): React.ReactNode {
+    const { className, size, style } = this.props;
+
+    return (
+      <div
+        className={`container ${className}`}
+        style={style}
+      >
+        <svg
+          height={size}
+          viewBox='0 0 64 64'
+          width={size}
+        />
+      </div>
+    );
+  }
+}