ci: add Travis config

.travis.yml

@@ -0,0 +1,24 @@
+language: node_js
+node_js:
+    - 8
+
+notifications:
+  email: false
+
+cache:
+  directories:
+    - "node_modules"
+
+jobs:
+    include:
+        - stage: branch test
+          script: npm test && npm run build
+        - stage: npm publish
+          script: npm test && npm run build
+          after_success: npm run semantic-release
+
+stages:
+  - name: branch test
+    if: branch != master
+  - name: npm publish
+    if: branch = master