fix(package): update yeoman-generator to version 3.1.0

Closes #15

Author: greenkeeper[bot]

package.json

@@ -30,7 +30,7 @@
   "dependencies": {
     "chalk": "^2.1.0",
     "lodash": "^4.17.4",
-    "yeoman-generator": "^2.0.1",
+    "yeoman-generator": "^3.1.0",
     "yosay": "^2.0.1"
   },
   "jest": {