Adding a method for retrieving the list of users in a search by skill
Adding a test for the InvalidArgumentException and adding "self" to the references to the constants
Adding a method to search for people by name and the test for the invalid argument for issue #90
Making changes from @jcarouth's notes on the PR
Added another fix that I missed
Merge pull request #98 from phpmentoring/user_search

Support user search in the service backend.