Version 2.0.0

• Add support for running on Ruby 1.8.7. (#89 and #90)
• Add appraisal list subcommand to list all appraisals. (#74)
• Add support for nesting of Bundler block DSL. (#84)
• Add Travis CI configuration helper which will prints out a proper Travis CI
  gemfiles configuration to be put in .travis.yml file, and warns you if
  your configuration is outdated. (#65)
• Add appraisal --version to print out current version. (#80)
• Add gemspec support in group directive. (#76)
• Add platform alias to platforms, and remove groups directive as it is
  not in Bundler (#78 and #83)
• Fix problem when running appraisal --help without Appraisals file.
• Fix problem when dependency in Appraisals does not take precedent over
  dependency listed in Gemfile.
• Fix problem where duplicate source will be listed twice. (#85)
• Fix problem with relative path prefixing in gem, path, and git
  direcitve. (#82)
• Fix problem with spaces in command line argument. (#86)
• Fix problem while running in vendored environment. (#13, #30 and #87)