PASS: agent_server.HttpData exists
PASS: agent_server.HttpData.req is a Map
PASS: agent_server.HttpData.res is a Map
Addet a HttpSupplier abstract class.
Refactored unittest.
HttpMiddleware.run returns the same object back.

PASS: agent_server.HttpMiddleware.run returns the same object back.
PASS: agent_server.HttpMiddleware.stack is a list
middleware on the .stack is run()

PASS: agent_server.HttpMiddleware middleware on the .stack is run()