Relation#all is deprecated in Rails 4, use Relation#to_a instead

We should use Relation#to_a instead of Relation#all, which will be removed in Rails 4.1. Maybe its a good time to make this small adjustment now. The pull request is passing tests and ready to merge! Also, how do you feel about upgrading the demo project to Rails 4?

    DEPRECATION WARNING: Relation#all is deprecated. If you want to eager-load a relation,
    you can call #load (e.g. `Post.where(published: true).load`). If you want to get an array of 
    records from a relation, you can call #to_a (e.g. `Post.where(published: true).to_a`). (called 
    from followers at .../socialization/lib/socialization/stores/active_record/follow.rb:69)