Update babylon to latest beta version

Author: danez

package.json

@@ -34,7 +34,7 @@
   "dependencies": {
     "async": "^2.1.4",
     "babel-runtime": "^6.9.2",
-    "babylon": "7.0.0-beta.29",
+    "babylon": "7.0.0-beta.31",
     "commander": "^2.9.0",
     "doctrine": "^2.0.0",
     "node-dir": "^0.1.10",

yarn.lock

@@ -805,10 +805,6 @@ babel-types@^6.18.0, babel-types@^6.19.0, babel-types@^6.24.1, babel-types@^6.26
     lodash "^4.17.4"
     to-fast-properties "^1.0.3"
 
-[email protected]:
-  version "7.0.0-beta.29"
-  resolved "https://registry.yarnpkg.com/babylon/-/babylon-7.0.0-beta.29.tgz#6a3e0e6287390385a36f5511e7f94db8618574ae"
-
 [email protected], babylon@^7.0.0-beta.31:
   version "7.0.0-beta.31"
   resolved "https://registry.yarnpkg.com/babylon/-/babylon-7.0.0-beta.31.tgz#7ec10f81e0e456fd0f855ad60fa30c2ac454283f"