Revert Lerna dependency, there's too many bugs in v3

Author: Timer

package.json

@@ -22,7 +22,7 @@
     "eslint": "4.19.1",
     "execa": "1.0.0",
     "husky": "^0.14.3",
-    "lerna": "3.4.0",
+    "lerna": "2.9.1",
     "lerna-changelog": "^0.8.0",
     "lint-staged": "^7.0.5",
     "meow": "^5.0.0",