As a developer, I want a consistent and easy to use RESTful API following the "principle of least surprise".

Audit RESTful endpoints for:

• Consistent (libpod) or Compatible (compat) HTTP return codes
• Improved messaging
  • No more "Something bad happened" messages
• Should returned JSON continue to be HTML encoded?
• Provide references to allow detailed documentation for all fields
• Consistent input/output
  • single input  should not result in a collection output
  • Content-Type header set to payload contents
• Flag unused types and references currently defined in swagger

Card should result in cards detailed needed changes.

Associated Cards:

• https://issues.redhat.com/browse/RUN-1217
• https://issues.redhat.com/browse/RUN-1260