chore(package): update flow-bin to version 0.51.0

Author: greenkeeper[bot]

package.json

@@ -47,7 +47,7 @@
     "eslint-plugin-prettier": "^2.1.2",
     "express": "^4.15.3",
     "express-graphql": "^0.6.6",
-    "flow-bin": "^0.49.1",
+    "flow-bin": "^0.51.0",
     "graphql": "^0.10.3",
     "graphql-compose": "^2.0.0",
     "jest": "^20.0.4",