Blueprint for Websockify security proxy framework

This blueprint proposes a generic framework for supporting
man-in-the-middle authentication and encryption between
Websockify and the hypervisor graphics servers.  It also
proposes a reference driver for that framework for TLS
security.

Spec for blueprint websocket-proxy-to-host-security

Change-Id: I23c5a43788afcb705b0d879cf5df4b49f0aa7a67
Previously-approved: juno
Merge "Blueprint for Websockify security proxy framework"