WHAT

Create a /apps/

endpoint to GET information on a single app with a list of versions and version specific information (num of clients, num of app launches, disabled, custom message)

See whiteboard session
https://drive.google.com/open?id=1umnk5NMCQqw6DMSMFuN1yYuye0AZObaU

WHY

Needed to display information for the detailed app view on the admin UI
Trello link