release v2.1.0 (2015-09-08)

• Fix Ubuntu 15.04 support.
• Improve platforms support using node['platform_family'] node attribute.
• Update chef links to use chef.io domain.
• Update contact information and links after migration.
• metadata: Add source_url and issues_url links.
• Documentation:
  • README: Add GitHub badge.
• Testing:
  • Some test files updated: .travis.yml, Berksfile, Gemfile, Rakefile.
  • Gemfile: Update RuboCop to 0.34.0.
  • Move ChefSpec tests to test/unit.
  • Replace all bats tests by Serverspec tests.
  • Add .kitchen.docker.yml file for kitchen-docker.
  • Run kitchen on Travis using kitchen-in-travis script.