Moving eslint-config-fbjs to devDependencies in package.json

Summary:
Having ``eslint-config-fbjs`` listed within ``dependencies`` in the package.json file causes ``npm install`` warnings for ESLint users with ``relay-compiler`` listed as a dependency.

This resolves this issue, yet allows Relay devs to still use the ESLint rules.
<img width="758" alt="screen shot 2017-08-28 at 11 12 24 am" src="https://user-images.githubusercontent.com/16157429/29782339-d627f40c-8be1-11e7-813b-b8256cddaa60.png">
Closes #2066

Reviewed By: leebyron

Differential Revision: D5718301

Pulled By: kassens

fbshipit-source-id: 9ad28efce2b7b0104a650e9202cc62c18c36673a

packages/relay-compiler/package.json

@@ -22,7 +22,6 @@
     "babel-types": "6.25.0",
     "babylon": "6.18.0",
     "chalk": "^1.1.3",
-    "eslint-config-fbjs": "^1.1.1",
     "fast-glob": "^1.0.1",
     "fb-watchman": "^2.0.0",
     "fbjs": "^0.8.1",