fix(package): update yargs to version 13.2.2

Closes #26

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
   "dependencies": {
     "commondir": "^1.0.1",
     "fs-extra": "^1.0.0",
-    "yargs": "^6.0.0",
+    "yargs": "^13.2.2",
     "glob": "^7.0.3",
     "rev-hash": "^1.0.0",
     "rev-path": "^1.0.0"