Implement Readable mocks on Request

[aboyce]

Mock implementations for the Express Request have not been implemented deep enough. These need to be implemented to prevent type errors when used.

Express Request hierarchy:

• express.Request ✔
• http.IncomingMessage ✔
• stream.Readable ❌
• event.EventEmitter ❌

Implement the properties and functions for stream.Readable and event.EventEmitter.

[aboyce]

Express Request hierarchy as part of v2 release:

• express.Request ✔
• http.IncomingMessage ✔
• stream.Readable ✔
• event.EventEmitter ✔