language: ruby
rvm:
  - 1.8.7
  - 1.9.2
  - 1.9.3
  - 2.0.0
  - 2.1.1
  - ruby-head
  - rbx-2.2.6
  - ree
  - jruby-19mode
  - jruby-head
matrix:
  allow_failures:
    - rvm: ruby-head
    - rvm: jruby-head
before_install:
  - sudo apt-get install -qq graphicsmagick

language: ruby
cache: bundler
bundler_args: --jobs=1 --retry=3
rvm:
  - 1.8.7
  - 1.9.2
  - 1.9.3
  - 2.0.0
  - 2.1.1
  - ruby-head
  - rbx-2.2.6
  - ree
  - jruby-19mode
  - jruby-head
matrix:
  allow_failures:
    - rvm: ruby-head
    - rvm: jruby-head
before_install:
  - sudo apt-get install -qq graphicsmagick

Fix Travis build for Rubinius
Fix Travis build for Rubinius

Installing gems with RubyGems <= 2.4.0 is not thread-safe, and because
of that Rubinius was failing when installing gems. The latest RubyGems,
2.4.1, allegedly fixes that problem, so I added

  gem update --system 2.4.1

to the Travis build. But that didn't work, the error was still there.
So I decided to just not install gems in parallel, and cache the
installed gems, so that step should still be fast enough.
