Updates for 2.1.4 release.
Merged r10865 and r10866 from trunk (#12431).
Merged r10838 from trunk (#12274).
Merged r10836 from trunk (#12298).
Merged r10837 from trunk (#12332).
Removed duplicated test.
Use Project.rebuild_tree! instead of .rebuild! in migration.
Adds a Project.rebuild_tree! method to force the rebuild of the nested set.
Fixed that Project.rebuild! sorts projects by id instead of name (#12431).
