Delegator factory based resolver instantiation

This feature is based off my research at http://ocramius.github.io/blog/zend-framework-2-delegator-factories-explained/

The usage of the delegator factory brings to 3 main advantages:
 - cleaner code
 - lazy instantiation of the real view resolver (saves CPU time)
 - removal of hacks around the service manager

Additionally, I killed support for PHP < 5.5.