Added support for cache hit counter
Added logging of caught exceptions
Added support for infinite lifetime (NULL / 0 seconds)
Replaced 'lifetime' property
Refactored 'expire' property to 'expire_at' which is a MongoDate
Adopted MongoDate with microsecond granularity, usefull to determine order of writing cache records
Added some documentation to improve auto-completion by IDE's
Prevent install of zf1-empty
Merge pull request #6 from holtkamp/mongo-date

Implemented support for MongoDate