Update awesome_nested_set

The stable release of awesome_nested_set isn't compatible with Rails 4.1;
running in production mode errors out at init.

Issue 253 suggests resolving with 3.0.0 RC
https://github.com/collectiveidea/awesome_nested_set/issues/253

Conflicts:
	Gemfile.lock

Gemfile

@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 
-# Use rails as framework 
+# Use rails as framework
 gem 'rails', '~> 4.1'
 
 # Use mysql as the database for Active Record
@@ -27,6 +27,7 @@ gem 'cancan'
 gem 'transitions', :require => %w( transitions active_record/transitions )
 
 # Use acts_as_commentable_with_threading for comments
+gem 'awesome_nested_set', '~> 3.0.0.rc.5'
 gem 'acts_as_commentable_with_threading'
 
 # Use haml as templating language
@@ -87,13 +88,13 @@ group :development, :test do
   gem 'shoulda'
 end
 
-# FIXME: We should use http://weblog.rubyonrails.org/2012/3/21/strong-parameters/ 
+# FIXME: We should use http://weblog.rubyonrails.org/2012/3/21/strong-parameters/
 gem 'protected_attributes'
 
 # We use this bootstrap/html5 rdoc generator
 gem 'rdoc-generator-fivefish'
 
-# We use factory_girl for seeds 
+# We use factory_girl for seeds
 gem 'factory_girl_rails'
 
 # Use guard and spring for testing in development