Beaker is a web session and general caching library that
includes WSGI middleware for use in web applications.

Features:
* Fast, robust performance
* Multiple reader/single writer lock system to avoid duplicate
  simultaneous cache creation
* Cache back-ends include dbm, file, memory, memcached, and database
  (Using SQLAlchemy for multiple-db vendor support)
* Signed cookie's to prevent session hijacking/spoofing
* Cookie-only sessions to remove the need for a db or file backend
  (ideal for clustered systems)
* Extensible Container object to support new back-ends
* Cache's can be divided into namespaces (to represent templates,
  objects, etc.) then keyed for different copies
* Create functions for automatic call-backs to create new cache
  copies after expiration
* Fine-grained toggling of back-ends, keys, and expiration per
  Cache object
