v0.3.0

• BC break: Rename Api to ActionSender to reflect its responsibility
  (#22)
  • Rename invalid action method logout() to proper logoff()
    (#17)
• Feature: Add Response::getCommandOutput() helper
  (#23)
• Feature: Emit "error" event for unexpected response messages
  (#21)
• Functional integration test suite
  (#18 / #24)