fix(package): update yeoman-generator to version 4.8.1

Closes #7

Author: greenkeeper[bot]

package.json

@@ -15,7 +15,7 @@
     "@gnodi/eslint-config": "^0.2.0",
     "chalk": "^1.1.3",
     "yeoman-assert": "^3.0.0",
-    "yeoman-generator": "^1.0.1",
+    "yeoman-generator": "^4.8.1",
     "yeoman-test": "^1.5.1",
     "yosay": "^2.0.0"
   },