Add PHPMemcachedAdmin 1.2.2 to view memcached stats

Now accessible via http://192.168.50.4/memcached-admin/ by default, PHPMemcachedAdmin provides a look at the various goings on of Memcached inside the virtual machine and can offer a valuable picture when troubleshooting caching issues.
Update README and Changelog to reflect phpMemcachedAdmin addition