Build and push releases to GitHub on new tags

Set up Travis CI integration, so that we build the application and
push the tarball to GitHub on every new annotated git tag.

Author: malor

.travis.yml

@@ -9,3 +9,15 @@ node_js:
 script:
   - npm run lint
   - npm run build
+
+before_deploy:
+  - export RELEASE_NAME="xsnippet_web-$(git describe --exact-match --abbrev=0).tar.gz"
+  - tar cvzf $RELEASE_NAME -C dist/ .
+
+deploy:
+  provider: releases
+  api_key: $GITHUB_TOKEN
+  file: $RELEASE_NAME
+  skip_cleanup: true
+  on:
+    tags: true