BUGFIX: make the system_user an elder (TL=4)

Otherwise it won't be able to create topic when the `min_trust_to_create_topic` is > 0

db/fixtures/005_users.rb

@@ -22,4 +22,5 @@ User.seed do |u|
   u.email_direct = false
   u.approved = true
   u.email_private_messages = false
+  u.trust_level = TrustLevel.levels[:elder]
 end

lib/guardian/topic_guardian.rb

@@ -27,18 +27,17 @@ module TopicGuardian
 
   # Creating Methods
   def can_create_topic?(parent)
-    user && user.trust_level >= SiteSetting.min_trust_to_create_topic.to_i && can_create_post?(parent)
+    user &&
+    user.trust_level >= SiteSetting.min_trust_to_create_topic.to_i &&
+    can_create_post?(parent)
   end
 
   def can_create_topic_on_category?(category)
-    can_create_topic?(nil) && (
+    can_create_topic?(nil) &&
-    !category ||
+    (!category || Category.topic_create_allowed(self).where(:id => category.id).count == 1)
-    Category.topic_create_allowed(self).where(:id => category.id).count == 1
-    )
   end
 
   def can_create_post_on_topic?(topic)
-
     # No users can create posts on deleted topics
     return false if topic.trashed?
 
@@ -82,4 +81,4 @@ module TopicGuardian
       (not(topic.private_message?) || authenticated? && (topic.all_allowed_users.where(id: @user.id).exists? || is_staff?))
     end
   end
-end
+end