Adds CircleCI config + Missing React dependency

Author: birdofpreyru

.circleci/config.yml

@@ -0,0 +1,53 @@
+version: 2
+jobs:
+  # Release.
+  # TODO: Probably, it is possible to reuse the test job below as a part of
+  # the release job; but as I don't know how to do it at the moment, let's
+  # just dublicate the logic for now.
+  release:
+    docker:
+      - image: circleci/node:8.9.4
+    steps:
+      - checkout
+      - restore_cache:
+          # Careful here, though, at the moment, there should be no problem
+          # to reuse the same cache of "node_modules" between test and release
+          # jobs.
+          key: test-node-modules-{{ checksum "package-lock.json" }}
+      - run: npm install
+      - save_cache:
+          key: test-node-modules-{{ checksum "package-lock.json" }}
+          paths:
+            - node_modules
+      - run: npm test
+      - run: echo "//registry.npmjs.org/:_authToken=$NPM_TOKEN" >> ~/.npmrc
+      - run: npm publish
+
+  # Just tests commited code.
+  test:
+    docker:
+      - image: circleci/node:8.9.4
+    steps:
+      - checkout
+      - restore_cache:
+          key: test-node-modules-{{ checksum "package-lock.json" }}
+      - run: npm install
+      - save_cache:
+          key: test-node-modules-{{ checksum "package-lock.json" }}
+          paths:
+            - node_modules
+      - run: npm test
+
+workflows:
+  version: 2
+  build:
+    jobs:
+      - release:
+          filters:
+            branches:
+              only: master
+      - test:
+          filters:
+            branches:
+              ignore: master
+