chore(ci): Config circle ci (#207)

* chore: add circleci

* chore: add circle-ci
* also use npm ci for testing installs, which requires the package-lock and package.json to be in sync

.circleci/config.yml

@@ -0,0 +1,49 @@
+# Javascript Node CircleCI 2.1 configuration file
+#
+# Check https://circleci.com/docs/2.0/language-javascript/ for more details
+#
+version: 2.1
+
+commands:
+  test-nodejs:
+    steps:
+      - run:
+          name: 'Output Node Version'
+          command: 'node -v'
+
+      - checkout
+
+      # install with npm ci to make sure package.json and lock are N'Sync
+      # No need to cache node_modules since npm ci will delete it
+      - run: npm ci
+
+      # run tests!
+      - run: npm run ci
+
+jobs:
+  node10:
+    docker:
+      - image: circleci/node:10
+    steps:
+      - test-nodejs
+
+  node12:
+    docker:
+      - image: circleci/node:12
+    steps:
+      - test-nodejs
+
+workflows:
+  version: 2
+  test_node_versions:
+    jobs:
+      - node10:
+        filters:
+          branches:
+            ignore:
+              - gh-pages
+      - node12:
+        filters:
+          branches:
+            ignore:
+              - gh-pages

package.json

@@ -8,7 +8,7 @@
     "test": "tape test/*-test.js | tap-spec",
     "coverage": "nyc npm test",
     "coverage:html": "nyc npm test && nyc report --reporter=html",
-    "coveralls": "nyc npm test && nyc report --reporter=text-lcov | coveralls",
+    "coveralls": "nyc npm test && nyc report && if [ $COVERALLS_REPO_TOKEN'' != '' ] ; then nyc report --reporter=text-lcov | coveralls; fi",
     "ci": "npm run lint && npm run coveralls",
     "docs": "documentation build lib/** -f html -o docs",
     "release": "standard-version -a"