refactor: mkdir plugins

Author: fengzilong

packages/pages-plugin-layout-now/.gitkeep

@@ -0,0 +1,3 @@
+export default function ( ctx ) {
+  ctx.data
+}

plugins/pages-plugin-layout-now/browser.js

@@ -0,0 +1,18 @@
+module.exports = async function ( ctx ) {
+  ctx.rebuild()
+  ctx.chainWebpack( webpack => {
+
+  } )
+
+  ctx.gatherer.watchConfig( 'layout', () => {
+    ctx.writeFile(  )
+    ctx.addRoute(  )
+  } )
+
+  ctx.gatherer.watchFile( '', () => {
+
+  } )
+
+  // like ctx.body
+  ctx.data = { foo: 'bar' }
+}