chore(package): update nsp to version 3.1.0

Closes #28

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
     "knex": "0.13.0",
     "mocha": "^3.1.0",
     "npm-check": "^5.2.3",
-    "nsp": "^2.6.1",
+    "nsp": "^3.1.0",
     "objection": "^0.8.0",
     "pg": "^7.3.0",
     "pg-escape": "^0.2.0",