chore(package): update pg to version 5.0.0 (#249)

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -53,7 +53,7 @@
     "eslint": "^1.7.3",
     "istanbul": "^0.4.0",
     "mocha": "^2.2.5",
-    "pg": "^4.4.2",
+    "pg": "^5.0.0",
     "pg-hstore": "^2.3.2",
     "sequelize": "^3.16.0",
     "sinon": "^1.15.4",