Make spawning with memcache in rails 3.2.X work properly again - the reset method on Rails.cache was not being defined.

We were seeing the classic connection sharing problems with memcache as Rails.cache.reset was not being called.

It seems odd to check that the class has been autoloaded?
  At least in rails 3.2 when this gem is loaded, ActiveSupport::Cache is not autoloaded yet,
  hence the second condition is false. Remove that condition as it doesn't seem needed