Update linting script in package.json.

(per new ember-cli blueprint, w/ mirage directory added)

Author: CvX

package.json

@@ -17,7 +17,7 @@
   },
   "scripts": {
     "build": "ember build",
-    "lint": "eslint app addon blueprints config server test-support tests *.js",
+    "lint:js": "eslint ./*.js app config lib mirage server tests",
     "start": "ember serve",
     "start:live": "ember serve --proxy https://crates.io",
     "start:local": "ember serve --proxy http://127.0.0.1:8888",