Ensure directory listing is consistently ordered.
Ensure directory listing is consistently ordered.

When loading all config files in a directory, ensure that they load in
a consistent order by pre-sorting. Fixes a [build failure][] that I was
unable to replicate locally on Ruby 2.0.0-p353.

[build-failure]: https://travis-ci.org/3den/dot_hash/jobs/16335796

3den/dot_hash