add lerna

lerna.json

@@ -0,0 +1,8 @@
+{
+  "npmClient": "yarn",
+  "useWorkspaces": true,
+  "packages": [
+    "packages/*"
+  ],
+  "version": "independent"
+}

package.json

@@ -21,7 +21,9 @@
   },
   "private": true,
   "workspaces": {
-    "packages": ["packages/*"],
+    "packages": [
+      "packages/*"
+    ],
     "nohoist": []
   },
   "scripts": {
@@ -219,6 +221,7 @@
     "jquery-slimscroll": "^1.3.8",
     "jquery-ui": "^1.12.1",
     "jquery.cookie": "~1.4.1",
+    "lerna": "^4.0.0",
     "load-css-file": "^1.0.0",
     "lodash-webpack-plugin": "^0.11.5",
     "markdown-it": "^10.0.0",