Fix remaining rubocop problems

.rubocop.yml

@@ -94,6 +94,9 @@ Style/AndOr:
 Metrics/BlockNesting:
   Max: 4
 
+Metrics/ClassLength:
+  Max: 550
+
 # avoid redundunt curly braces when it is obvious that hash is used
 Style/BracesAroundHashParameters:
   Enabled: true

.rubocop_todo.yml

@@ -22,11 +22,6 @@ Lint/IneffectiveAccessModifier:
 Metrics/AbcSize:
   Max: 75
 
-# Offense count: 7
-# Configuration parameters: CountComments.
-Metrics/ClassLength:
-  Max: 514
-
 # Offense count: 12
 Metrics/CyclomaticComplexity:
   Max: 12

app/models/registration.rb

@@ -52,7 +52,7 @@ class Registration < ActiveRecord::Base
   end
 
   def registration_limit_not_exceed
-    if self.conference.registration_limit>0 && self.conference.registrations(:reload).count >= self.conference.registration_limit
+    if conference.registration_limit > 0 && conference.registrations(:reload).count >= conference.registration_limit
       errors.add(:base, 'Registration limit exceeded')
     end
   end