specified bundle version to 1.11.x for TravisCI.

Author: takaokouji

.travis.yml

@@ -12,7 +12,7 @@ env:
 before_install:
  - sudo apt-get update -qq
  - sudo apt-get install -qq libsdl1.2-dev libsdl-image1.2-dev libsdl-mixer1.2-dev timidity libsdl-ttf2.0-dev libsdl-sge-dev fonts-horai-umefont fonts-ipafont
- - gem update bundler
+ - gem install bundler -v '~> 1.11.0'
  - gem uninstall -i /home/travis/.rvm/gems/ruby-2.1.5@global bundler
 
 before_script: