Rails 4 compatibility 

Attached some changes necessary to get it working on Rails 4.

* removes attr_accessible in favor for "strong_parameters".

  I did not find a common use case where you update the votes directly, anyway. If you still need to write some controller for CRUDing votes, you have access to "vote_params" and "votable_params" in your controllers so you can safely pass in the parameters. It is defined as a scalar-permit, so you might wanna use voter_params(params[:my_vote_name_other_than_vote]) if you don't have the attributes at params[:vote].

  I'd suggest to remove that in future, if no good use case is found. I did not test this (there was no test case for the attr_accessible effects before).
  
* changes scopes to lambdas
* changes t.references to t.integer in migrations (is this good practice? if not, just skip it)
* updates gem file

So, this should work for Rails 3.2.x and Rails 4, in case you are not using the params-thing.