SASL Support in Drupal 8 version

1. +++ b/README.txt
   @@ -225,3 +225,28 @@ Other options you could experiment with:
   +  $conf['memcache_options'] = array(
   +    Memcached::OPT_BINARY_PROTOCOL => TRUE,
   +  );
   

   The format of these is incorrect I think? These are all in settings now, like you have above for the sasl credentials.

   I think this should be:

   $settings['memcache']['options'] = [
     \Memcached::OPT_BINARY_PROTOCOL => TRUE,
   ];
   

2. +++ b/README.txt
   @@ -225,3 +225,28 @@ Other options you could experiment with:
   +  $conf['memcache_sasl_username'] = 'yourSASLUsername';
   +  $conf['memcache_sasl_password'] = 'yourSASLPassword';
   

   These are old D7 settings are duplicates of the correct sasl array above?

3. +++ b/src/DrupalMemcacheFactory.php
   @@ -49,6 +49,11 @@ class DrupalMemcacheFactory {
   +  protected $memcacheSasl = array();
   

   I think just @sasl is an ok name. Although, looking at this property, it doesn't seem to be used in the patch?

This looks good now - thanks. We could check that username and password are explicitly set to avoid warnings but I think this is fine. Committed and pushed.