Add a Prof M customization based on the Recent Changes API

[lschaefer-sugarcrm]

The Recent Changes API (https://github.com/sugarcrm/BuildingBlocks/tree/master/packages/RecentChangesAPI) is a custom endpoint that identifies Users who have had recent changes to their assigned records. It returns an array that includes the time on the server when the request was executed and a list of user IDs, usernames, and changed modules for users with changes.

We should develop a story around the Recent Changes API that makes sense in the context of Professor M and add an adapted version of the custom endpoint to the school repo.

This completed story should have associated automated tests. Perhaps @rhoggSugarcrm has some ideas on how we can test this endpoint using Thorn. He mentioned interest in writing another Thorn blog post on testing a custom endpoint. :-) If we go with Thorn, we'll have to add the infrastructure to run the tests locally, in Travis CI builds, and in Jenkins builds.

Suggestion from @skymeyer when he was reviewing the Recent Changes API in the Building Blocks repo: refactor the boolean constraint into a custom constraint.