add missing awesome_nested_set 2.1.6 files (#6579)

https://github.com/collectiveidea/awesome_nested_set/commit/64cc8bc8cf93e8859a21bcf25c36675080e42ce6

git-svn-id: http://svn.redmine.org/redmine/trunk@13013 e93f8b46-1217-0410-a6f0-8f06a7374b81
fix awesome_nested_set test failure (#6579)

git-svn-id: http://svn.redmine.org/redmine/trunk@13014 e93f8b46-1217-0410-a6f0-8f06a7374b81