import awesome_nested_set 2.1.5

https://github.com/collectiveidea/awesome_nested_set/commit/60fe4f69e4d6c3052bb45fb3e0a118ca201d9054

--HG--
extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012677
add lib/plugins/awesome_nested_set/init.rb

--HG--
extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012678
apply Redmine awesome_nested_set 2.1.5 modification

--HG--
extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012679