Support for consistent ordering of configtree nodes is required for:
(1) Unit tests of the config_diff algorithm, in order to establish identity of configtrees before/after application, for example:
diff(left, right) => add, subtract, intersection; consequently, one wants to check right == union(intersection, add) and left == union(intersection, subtract)
(2) We currently rely on ordering from vyatta-cfg; when we move away from reliance on the legacy backend, we will need a replacement.