Document memcached.sess_binary_protocol

And remove a TODO found in the code for allowing users to configure
whether or not to use binary protocols for sessions.

For issue #233

Author: TysonAndre

memcached.ini

@@ -63,9 +63,11 @@ memcached.sess_remove_failed_servers = Off
 ; which could have old data or no data at all
 memcached.sess_number_of_replicas = 0
 
-; memcached session binary mode
-; libmemcached replicas only work if binary mode is enabled
-memcached.sess_binary = Off
+; Use the memcached binary protocol for memcached sessions (Instead of the text protocol)
+; libmemcached replicas work only if binary mode is enabled.
+; However, certain proxies (such as twemproxy) will work only if the binary protocol is disabled.
+; Default is On. In older versions of php-memcached, this setting was Off and was called memcached.sess_binary.
+memcached.sess_binary_protocol = On
 
 ; memcached session replica read randomize
 memcached.sess_randomize_replica_read = Off

php_memcached.c

@@ -19,7 +19,6 @@
 /* TODO
  * - set LIBKETAMA_COMPATIBLE as the default?
  * - fix unserialize(serialize($memc))
- * - ability to set binary protocol for sessions
  */
 
 #include "php_memcached.h"