Don't deploy if you're not on master

Thank you:
https://github.com/travis-ci/travis-ci/issues/5419#issuecomment-222815942

.travis.yml

@@ -22,11 +22,11 @@ deploy:
     api_key: $NPM_TOKEN
     on:
       tags: true
-      branch: master
+      condition: $(git branch --contains $TRAVIS_TAG | grep -l '^[\* ] master$')
   - provider: pages
     skip_cleanup: true
     github_token: $GITHUB_TOKEN  # Set in the settings page of your repository, as a secure variable
     keep_history: true
     on:
       tags: true
-      branch: master
+      condition: $(git branch --contains $TRAVIS_TAG | grep -l '^[\* ] master$')