Release v0.2.1'

* release/0.2.1:
  Version bumped to 0.2.1
  Gemfile ang gemspec updated
  Added shortcuts for setting the CPU count and memory size [GH-71]
  Refactoring of actions 'Import', 'Export' and 'Package'
  'config.rb': _detected_errors usage added
  'actions.rb' refactoring
  Action 'SetName' added
Travis: install Bundler 1.5.2 for tests
Travis: install Bundler 1.5.2 for tests