Call #to_s on id when passed to enqueue

This will become necessary when Mongoid bumps to 4.0.0, so preemptively
make this change now.

Signed-off-by: David Celis <me@davidcel.is>

Author: davidcelis

lib/recommendable.rb

@@ -24,6 +24,7 @@ def query(klass, ids)
 
     def enqueue(user_id)
       user_id = user_id.id if user_id.is_a?(Recommendable.config.user_class)
+      user_id = user_id.to_s
 
       if defined?(::Sidekiq)
         Recommendable::Workers::Sidekiq.perform_async(user_id)

lib/recommendable/helpers/calculations.rb

@@ -169,7 +169,7 @@ def predict_for(user_id, klass, item_id)
           liked_by_set = Recommendable::Helpers::RedisKeyMapper.liked_by_set_for(klass, item_id)
           disliked_by_set = Recommendable::Helpers::RedisKeyMapper.disliked_by_set_for(klass, item_id)
           similarity_sum = 0.0
-   
+
           similarity_sum += similarity_total_for(user_id, liked_by_set)
           similarity_sum -= similarity_total_for(user_id, disliked_by_set)
 
@@ -180,7 +180,7 @@ def predict_for(user_id, klass, item_id)
           prediction = similarity_sum / (liked_by_count + disliked_by_count).to_f
           prediction.finite? ? prediction : 0.0
         end
-        
+
         def similarity_total_for(user_id, set)
           similarity_set = Recommendable::Helpers::RedisKeyMapper.similarity_set_for(user_id)
           ids = Recommendable.redis.smembers(set)