add missing files

app/models/concerns/thumbnailable.rb

+module Thumbnailable
+  extend ActiveSupport::Concern
+
+  included do
+    has_attached_file :thumbnail, styles: { medium: '530x300', small: '250x140' }
+    validates_attachment_content_type :thumbnail, content_type: ['image/jpg', 'image/jpeg', 'image/png', 'image/gif']
+  end
+
+end

app/views/follows/_button.html.erb

+<% follow_text = current_user.following?(followable) ? 'Deixar de seguir' : 'Seguir' %>
+<%= link_to follow_text, follow_user_path(id: current_user.id, followable_type: followable.class.name, followable_id: followable.id), method: :post, remote: true, class: 'btn btn-default follow-button' %>

db/migrate/20160303120433_add_counter_to_user_collection.rb

+class AddCounterToUserCollection < ActiveRecord::Migration
+  def change
+    add_column :collections, :follows_count, :integer, default: 0
+    add_column :users, :follows_count, :integer, default: 0
+  end
+end

db/migrate/20160304100533_change_learning_object_score.rb

+class ChangeLearningObjectScore < ActiveRecord::Migration
+  def change
+    change_column :learning_objects, :score, :float, default: 0.0
+  end
+end

db/migrate/20160304102333_add_thumbnail_for_collections.rb

+class AddThumbnailForCollections < ActiveRecord::Migration
+  def change
+    add_attachment :collections, :thumbnail
+  end
+end