Check location of Kibana on postinstall

cli.js

@@ -77,5 +77,11 @@ program
     });
   }));
 
+program
+  .command('postinstall')
+  .action(taskRunner(function (command) {
+    run('postinstall');
+  }));
+
 program
   .parse(process.argv);

lib/tasks.js

@@ -3,11 +3,13 @@ const startTask = require('../tasks/start');
 const testAllTask = require('../tasks/test/all');
 const testBrowserTask = require('../tasks/test/browser');
 const testServerTask = require('../tasks/test/server');
+const postinstallTask = require('../tasks/postinstall');
 
 module.exports = {
   build: buildTask,
   start: startTask,
   testAll: testAllTask,
   testBrowser: testBrowserTask,
   testServer: testServerTask,
+  postinstall: postinstallTask
 };

tasks/postinstall/index.js

@@ -0,0 +1,25 @@
+const resolve = require('path').resolve;
+const statSync = require('fs').statSync;
+
+module.exports = function (plugin, run, options) {
+  if (
+    fileExists(resolve(plugin.root, '../kibana/package.json')) &&
+    !fileExists(resolve(plugin.root, '../../kibana/package.json'))
+  ) {
+    process.stdout.write(
+      '\nWARNING: Kibana now requires that plugins must be located in ' +
+      '`../kibana-extra/{pluginName}` relative to the Kibana folder ' +
+      'during development. We found a Kibana in `../kibana`, but not in ' + 
+      '`../../kibana`.\n'
+    )
+  }
+};
+
+function fileExists(path) {
+  try {
+    const stat = statSync(path);
+    return stat.isFile();
+  } catch (e) {
+    return false;
+  }
+}