Bump ARel to 2.1.3

Gemfile

@@ -5,7 +5,7 @@ gemspec
 if ENV['AREL']
   gem "arel", :path => ENV['AREL']
 else
-  gem "arel", '~> 2.1.0'
+  gem "arel", '~> 2.1.3'
 end
 
 gem "coffee-script"

activerecord/activerecord.gemspec

@@ -21,6 +21,6 @@
 
   s.add_dependency('activesupport', version)
   s.add_dependency('activemodel',   version)
-  s.add_dependency('arel',          '~> 2.1.1')
+  s.add_dependency('arel',          '~> 2.1.3')
   s.add_dependency('tzinfo',        '~> 0.3.27')
 end