Move key versioner code to pyramid_caching.key_versioners
Update (zope) interfaces for ICacheClient and IKeyVersioner
Add a redis extension providing ICacheClient and IKeyVersioner
Tests for redis extension
Remove umemcache extension
Remove plurials from pyramid_caching.versioners and .key_versioners
Add a pyramid_caching.exc.Base exception
Update changelog
Merge pull request #4 from pior/master

Add a caching extension for redis