Redis rake tasks

[javidjamae]

This PR adds a set of rake tasks that can be used along with the RedisRepository.

[javidjamae]

@mgsnova What are your thoughts on this PR?

[javidjamae]

@mgsnova Never mind, I'm closing this. It has a few issues and I don't have time to dig into it right now.

[mgsnova]

Sorry for the late response. I'm not sure if it will be good having that much special functionality for redis, or any other data source. The other would than lack this functionality.

[javidjamae]

@mgsnova - I was actually thinking that I could expose (most of) the same functionality for the other repositories and make the tasks look like:

rake feature:enable[asdf]
rake feature:list
rake feature:switch[asdf]
rake feature:disable[asdf]
etc...

If you're open to having it be available across all the repositories, and throw an unsupported exception when you can't do a particular operation with a given repository, then I'll take another look at it down the road.