Fixed tests by downgrading boom

Author: niftylettuce

package.json

@@ -16,7 +16,7 @@
     "ava": "^0.22.0",
     "babel-cli": "^6.26.0",
     "babel-preset-env": "^1.6.1",
-    "boom": "^7.1.1",
+    "boom": "^5.1.0",
     "codecov": "^2.3.0",
     "cross-env": "^5.0.5",
     "eslint": "^4.5.0",