Draft asyncio API

1. Support basic data communications use cases with asyncio semantics, ie. awaitable operations

• sending WS-Discovery SOAPEnvelope message objects as defined in the generic base daemon
• sending WS-Discovery UDP messsage objects with support for unicast, multicast, retrying etc.
• receiving WS-Discovery SOAPEnvelope message objects as defined in the generic base daemon

2. Support additional use cases for integrating WS-Discovery into asyncio-based applications

• TBD