Pull NovaWebSocketProxy class out of nova-novncproxy binary

To allow sharing of proxy code between nova-novncproxy and
nova-spicehtml5proxy, pull the NovaWebSocketProxy class
out of nova-novncproxy into a new nova/console/websocketproxy.py
file

Adds previously missing websockify dep to pip-requires.

Blueprint: libvirt-spice
Change-Id: If1334256680e7075598f00ce153cf6f021cc720f
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Add nova-spicehtml5proxy helper

Add nova-spicehtml5proxy which provides a websockets proxy,
equivalent to nova-novncproxy

Blueprint: libvirt-spice
Change-Id: I48be78c97bb7dd6635fd4bba476ef22701418ba1
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Merge "Pull NovaWebSocketProxy class out of nova-novncproxy binary"
Merge "Add nova-spicehtml5proxy helper"