Initial testing with jest (#133)

* 🎉 initial testing with jest

* 👌 update test script names & remove package-lock.json

* 👌 add 'yarn test' step to circle-ci build workflow

.circleci/config.yml

@@ -53,9 +53,9 @@ jobs:
           name: eslint
           command: yarn run eslint
 
-      # - run:
-      #     name: brakeman
-      #     command: brakeman
+      - run:
+          name: test
+          command: yarn test
 
       - run:
           name: Copy files