Official Docker image (#46)

* Initial Dockerfile

* Docker added to Readme

* Added Docker to Travis

.dockerignore

@@ -0,0 +1,50 @@
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+# vercel
+.vercel
+
+# IDEs
+/.vscode/
+/.idea/
+
+# cypress
+cypress/videos
+cypress/screenshots
+
+# next-pwa
+**/public/workbox-*.js*
+**/public/sw.js*
+**/public/worker-*.js*
+
+# git
+.git/
+.gitignore
+.gitattributes