DIR-89 Add support for slugs
You can now lookup departments, groups, and people by their slug if the slug exists. The old id method also still works.
Moving set_object method into application controller
This reduces some code duplication.
set `to_param` method on person, department, and group to include slug if available
Use slug in url from search result.
slug isn't currently being indexed, but it will be. I have a PR open for this https://github.com/biola/buweb-content-models/pull/82
Merge pull request #38 from biola/add_slug_support

DIR-89 Add support for slugs