Add publishing of artefacts

Author: jnavila

.travis.yml

@@ -9,6 +9,22 @@ before_install:
  - wget https://raw.githubusercontent.com/progit/progit2-pub/master/Rakefile
  - bundle install
 script: bundle exec rake book:build
+after_success: bundle exec rake book:tag
+deploy:
+  provider: releases
+  file:
+  - progit.epub
+  - progit.mobi
+  - progit.pdf
+  skip_cleanup: true
+  on:
+    tags: true
+  api-key: $GITHUB_API_TOKEN
+branches:
+  only:
+  - master
+  - /^2\.1(\.\d+)+$/
+
 addons:
   apt:
     packages: