fix bug, reject subjects that dont have highlights

Signed-off-by: Matheus Agio Nerone <man13@inf.ufpr.br>

app/controllers/welcome_controller.rb

@@ -12,7 +12,7 @@ class WelcomeController < ApplicationController
     end
 
     @subjects = subject_repository.all_from_offset_to_limit 0, 10
-    @subjects.reject{|s| not s.highlights.present?}
+    @subjects.reject!{|s| s.highlights.blank?}
     @subjects = @subjects.take(6)
   end