back out r12679 awesome_nested_set 2.1.5 modification

git-svn-id: http://svn.redmine.org/redmine/trunk@12684 e93f8b46-1217-0410-a6f0-8f06a7374b81
graft r5285 to awesome_nested_set 2.1.5 (#7920)

git-svn-id: http://svn.redmine.org/redmine/trunk@12685 e93f8b46-1217-0410-a6f0-8f06a7374b81
remove unneeded Project#acts_as_nested_set :order => 'name' option

git-svn-id: http://svn.redmine.org/redmine/trunk@12686 e93f8b46-1217-0410-a6f0-8f06a7374b81