chore(deps): update deps

No change to logic, update deps for security reasons.

Test: npm test
Test: npm run lint

Author: nfischer

.npmrc

@@ -0,0 +1,3 @@
+# We can't use lockfiles because npm@5 and npm@6 disagree about the syntax (and
+# will modify the lockfile when we run `npm install`).
+package-lock=false

package.json

@@ -27,14 +27,14 @@
     "index.js"
   ],
   "devDependencies": {
-    "eslint": "^3.1.1",
-    "eslint-config-airbnb-base": "^4.0.2",
-    "eslint-plugin-import": "^1.11.1",
-    "mocha": "^2.5.3",
+    "eslint": "^5.16.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.17.3",
+    "mocha": "^6.1.4",
     "shelljs": "^0.8.1",
     "shelljs-changelog": "^0.2.2",
     "shelljs-release": "^0.2.0",
-    "should": "^10.0.0"
+    "should": "^13.2.3"
   },
   "peerDependencies": {
     "shelljs": "^0.8.1"