[#3684] Polyfill support for version-dependent classes

- Per ideas from @ircmaxell, removed the conditional declaration of classes in
  favor of an autoloading solution. If using 5.3.3, composer will now load an
  alternate Zend\Stdlib\ArrayObject implementation.

  Both the project- and component-level composer.json files were modified so
  that the change will take place regardless of whether you install the full
  framework or just the component.

- Made changes to the php-code-sniffer configuration to ensure that the
  PHP-5.3.3-specific ArrayObject implementation is not checked, as it violates
  PSR-0 intentionally.

  - Realized that travis-build could be simplified, as .php_cs has the expected
    configuration for the full framework.

This builds on the ideas in #3684 and addresses the concerns about having the solution work for the individual component install versus a full framework install.