Run against Rails 4 and Ruby 2.0

This doesn't _require_ Rails 4 / Ruby 2.0 to work, as it is on
allow_failures, but at least you can track compatibility.
Merge pull request #181 from steveklabnik/master

Run tests against Rails 4 and Ruby 2.
Redis::Factory => Redis::Store::Factory
fix CI script
Merge branch 'master' into redis-options

merging master