Configure .travis.yml to publish l10n (#3)

Add .travis.yml, configured to use travis build stages. Releases should only happen if the branch is one listed in RELEASE_BRANCHES (set up in travis env variable)

.travis.yml

@@ -0,0 +1,23 @@
+language: node_js
+node_js:
+- 6
+- node
+cache:
+  directories:
+  - node_modules
+jobs:
+  include:
+    - stage: npm release
+      if: branch IN (env(RELEASE_BRANCHES))
+      node_js: 6
+      script: npm run build
+      before_deploy:
+      - npm --no-git-tag-version version $($(npm bin)/json -f package.json version)-prerelease.$(date +%s)
+      - git config --global user.email $(git log --pretty=format:"%ae" -n1)
+      - git config --global user.name $(git log --pretty=format:"%an" -n1)
+      deploy:
+        provider: npm
+        skip_cleanup: true
+        email: $NPM_EMAIL
+        api_key: $NPM_TOKEN
+