TODO

   1 * Store::MultiFile
   2     - hierarchal directory structure
   3     - filesystem based delete_expired_sessions
   4     - no locking (update?)
   5     - NFS friendly
   6 * Store::BerkeleyDB
   7     - complement FastMmap, but no LRU silliness
   8 * Catalyst::Plugin::Semaphores
   9     - possible drivers
  10         - memcached
  11         - flock
  12         - berkeleydb
  13         - fastmmap