add binary protocol option in MemcachedEngine
Merge pull request #5307 from shin1x1/add-binary-option-in-memcached-engine

SASL with Memcached is only supported with binary protocol
Merge branch 'master' of https://github.com/cakephp/cakephp

* 'master' of https://github.com/cakephp/cakephp:
  add binary protocol option in MemcachedEngine