Update .travis.yml

Adapted travis config to the old version

Author: pastatopf

.travis.yml

@@ -1,13 +1,13 @@
 language: ruby
+sudo: false	
 git:
   depth: false
 cache: bundler
 before_install:
-- bundle install
+ - wget https://raw.githubusercontent.com/progit/progit2-pub/master/bootstrap.sh
+ - sh bootstrap.sh	
 script: bundle exec rake book:build
-after_success: 
-- script/tag_on_master
-before_deploy: bundle install && bundle exec rake book:build
+after_success: bundle exec rake book:tag
 deploy:
   provider: releases
   file_glob: true