feat: migrate demo block to v2 (#26)

 export default {
   plugins: [
-    ['umi-plugin-block-dev', {}],
+    ['umi-plugin-block-dev', {
+      layout: 'ant-design-pro',
+    }],
     ['umi-plugin-react', {
       antd: true,
     }],

-export function getText() {
-  return 'I am a demo material of umi.';
-};

 {
   "name": "@umi-blocks/demo",
   "description": "a demo block of umi",
-  "blockConfig": {
-    "specVersion": "0.1"
+  "scripts": {
+    "dev": "umi dev"
+  },
+  "dependencies": {
+    "antd": "^3.10.9"
+  },
+  "devDependencies": {
+    "umi": "^2.3.0",
+    "umi-plugin-react": "^1.3.0",
+    "umi-plugin-block-dev": "^1.0.0"
   }
-}
\ No newline at end of file
+}

-export default {
-  'GET /api/test': { text: 'ok' },
-};

-import { getText } from '@/utils/helper';
 import styles from './index.less';
 import React from 'react';
 import { Button } from 'antd';
 
 export default () => {
-  return <Button className={styles.container}>{getText()}</Button>
+  return <Button className={styles.container}>Hello UmiJS!</Button>
 }