fix: add eslint's peer dependencies

Builds on Windows with Node 4 fails with a dependency missing error:
- https://tinyurl.com/ycf38c4h

Not really sure why this is needed, but it seems to be related to the
usage of @kentcdodds' eslint config (https://git.io/vF5Fe).

Here's some more details: https://git.io/vF5d5.

package.json

@@ -39,13 +39,15 @@
     "spawn-command": "0.0.2"
   },
   "devDependencies": {
+    "babel-eslint": "^8.0.2",
     "chai": "3.5.0",
     "chai-string": "1.3.0",
     "codecov": "1.0.1",
     "commitizen": "2.9.2",
     "cz-conventional-changelog": "1.2.0",
     "eslint": "3.12.2",
     "eslint-config-kentcdodds": "11.1.0",
+    "eslint-plugin-babel": "^4.1.2",
     "eslint-plugin-import": "2.2.0",
     "eslint-plugin-mocha": "4.7.0",
     "ghooks": "*",