Add a simple mini spinner

packages/common/vpu-mini-spinner.js

+import {html, LitElement, css} from 'lit-element';
+import commonUtils from './utils.js';
+
+
+class MiniSpinner extends LitElement {
+    constructor() {
+        super();
+    }
+
+    static get styles() {
+        return css`
+        .ring {
+          display: inline-block;
+          position: relative;
+          width: 1em;
+          height: 1em;
+        }
+        .ring div {
+          box-sizing: border-box;
+          display: block;
+          position: absolute;
+          width: 100%;
+          height: 100%;
+          border: 0.2em solid #000;
+          border-radius: 50%;
+          animation: ring 1.2s cubic-bezier(0.5, 0, 0.5, 1) infinite;
+          border-color: #000 transparent transparent transparent;
+        }
+        .ring div:nth-child(1) {
+          animation-delay: -0.45s;
+        }
+        .ring div:nth-child(2) {
+          animation-delay: -0.3s;
+        }
+        .ring div:nth-child(3) {
+          animation-delay: -0.15s;
+        }
+        @keyframes ring {
+          0% {
+            transform: rotate(0deg);
+          }
+          100% {
+            transform: rotate(360deg);
+          }
+        }`;
+    } 
+
+    render() {
+        return html`<div class="ring"><div></div><div></div><div></div><div></div></div>`;
+    }
+}
+
+commonUtils.defineCustomElement('vpu-mini-spinner', MiniSpinner);