chore(package): update eslint-plugin-flowtype to version 3.4.2

Closes #37

Author: greenkeeper[bot]

package.json

@@ -39,7 +39,7 @@
     "eslint": "^3.10.2",
     "eslint-config-iansinnott": "^1.0.1",
     "eslint-config-zen": "^3.0.0",
-    "eslint-plugin-flowtype": "^2.25.0",
+    "eslint-plugin-flowtype": "^3.4.2",
     "eslint-plugin-react": "^7.0.0"
   }
 }