Support for connection pooling in Memcache Store

Hey,

Any chance to get a connection pooling in memcache store?

We have that in Dalli’s Store: https://github.com/petergoldstein/dalli/blob/0af0200475db5ab6aa551dae026a932f6fece210/lib/active_support/cache/dalli_store.rb#L68

This would mean to add one more dependency to rails (connection_pool) to have this support.

Thanks!