New `self_and_ancestors_ids` method to get self id with ancestor_ids
Mention `self_and_ancestors_ids` in README
added passing tests and self_and_descendant_ids too, for extra credit. Thanks, kirs!
remove irritating stderr message about sleep
make travis run in a different database for every run
added test for remove_prefix_and_suffix
moved foreigner reference to ci gemfiles
Dropped support for rails 3.0. See https://travis-ci.org/mceachen/closure_tree/jobs/18563881
doc update [skip ci]