Consider providing RedisConnectionRepository and RedisUsersConnectionRepository officially

[caipanjin]

Thanks for working on creating such a nice project!

[Turbots]

Hey, I created a pull request which implements this, right here.

The Redis implementations of the ConnectionRepository and UsersConnectionRepository uses spring-data-redis-1.7.0.RC1 because that one introduces JPA repositories for Redis, which is awesome!

So I'm hoping they'll merge that PR into the next version of Spring-Social 😄