fix: drop support for node.js 4.x and 9.x (#244)

Author: JustinBeckwith

handwritten/firestore/.circleci/config.yml

@@ -65,13 +65,8 @@ jobs:
             npm install
           environment:
             NPM_CONFIG_PREFIX: /home/node/.npm-global
-      - run:
-          name: Run unit tests.
-          command: npm test
-      - run:
-          name: Submit coverage data to codecov.
-          command: node_modules/.bin/codecov
-          when: always
+      - run: npm test
+      - run: node_modules/.bin/codecov
   node8:
     docker:
       - image: 'node:8'
@@ -125,9 +120,5 @@ jobs:
         user: node
     steps:
       - checkout
-      - run:
-          name: Set NPM authentication.
-          command: 'echo "//registry.npmjs.org/:_authToken=${NPM_TOKEN}" > ~/.npmrc'
-      - run:
-          name: Publish the module to npm.
-          command: npm publish
+      - run: 'echo "//registry.npmjs.org/:_authToken=${NPM_TOKEN}" > ~/.npmrc'
+      - run: npm publish