add ci script

Author: calebmer

package.json

@@ -4,7 +4,8 @@
     "format": "prettier 'src/**/*.js' --write --print-width 80 --tab-width 2 --single-quote --trailing-comma all",
     "lint": "eslint 'src/**/*.js'",
     "test": "jest",
-    "test-watch": "jest --watch"
+    "test-watch": "jest --watch",
+    "ci": "npm run format && git diff --exit-code && npm run lint && npm test"
   },
   "babel": {
     "presets": [