(ci): add Travis CI support

- don't have tests yet, so for now just test lint, transpile/bundle,
  and pack
  - alter the test command to use the production build

Author: agilgur5

.travis.yml

@@ -0,0 +1,6 @@
+language: node_js
+# default is the very old 0.10.48; match local version instead
+node_js: '8.9'
+
+before_script: npm run lint
+script: npm test

package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "lint": "standard --parser babel-eslint",
     "lint:fix": "standard --parser babel-eslint --fix",
-    "test": "webpack && npm pack",
+    "test": "npm run dist && npm pack",
     "start": "webpack-dev-server -d --inline --hot",
     "dist": "webpack -p --config webpack.production.config.js",
     "pub": "npm run dist && npm publish"