Adds two new parameters to the employees shortcode to allow for sorting the directory by default when loading.  For example, [employees sort="last_name" order="ASC"] would sort by last names in ascending order (starting with A to Z).

git-svn-id: https://plugins.svn.wordpress.org/simple-intranet-directory/trunk@901924 b8457f37-d9ea-0310-8a92-e5e31aec5664