[neohub] Improved Web-Socket Communications

[andrewfg]

This PR makes a few improvements -- in the case when the communication is done via a web-socket -- as follows..

1. The server certificate is checked by a 'TlsTrustManagerProvider'. This avoids the 'trusting all certificates' warning on start-up.
2. Call throttling is now based on the time of the response (vs. the time of the request). This prevents exceeding the call rate limit if the hub server is busy. Thus preventing API exceptions.
3. Improved synchronization of API calls to prevent overlapping requests and responses. Thus preventing API exceptions.
4. The web-socket is explicitly closed (and reopened) when any exception occurs -- both local client exceptions and remote hub server errors. This prevents lock-up of the web-socket connection. Thus preventing subsequent API exceptions.

Signed-off-by: Andrew Fiddian-Green software@whitebear.ch

[lolodomo]

LGTM, thank you