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

Closes #27

Author: greenkeeper[bot]

package.json

@@ -29,7 +29,7 @@
     "gulp-git": "^1.6.0",
     "mkdirp": "^0.5.1",
     "string": "^3.3.1",
-    "yeoman-generator": "^1.0.0",
+    "yeoman-generator": "^3.1.0",
     "yosay": "^1.0.5"
   },
   "devDependencies": {