2.0.0

Breaking changes are explained in the Upgrades section in the docs.

• PHP 7.1 is now required
• Silex support was dropped
• SandFoxMe namespace was dropped
• Extensive refactoring and fixes in the ServiceManager support
• Tests!
• Integration\Slim\ContainerExportMiddleware and
  Integration\Psr15\ContainerExportMiddleware were combined into
  Integration\ContainerExportMiddleware
• Type strings for scalars now correspond to the values returned by get_debug_type()