engine: Integrate noVNC support

This patch integrates noVNC support in the engine.

Firstly it adds noVNC HTML5 client into the engine to be served by jBoss.

Secondly it adds websockify script customized for oVirt. In production
mode, this script must be able to verify signatures issued by the engine
(for validating vnc connection data).

The behavior of VNC console invocation now depends on configuration in db -
option noVncProxy. The possible values are:
 - 'Off' - feature is turned off - default.
 - 'Host[:port]' - feature is on - engine assumes the proxy is deployed on each
    host. port is optional, default is 6080.
 - 'Engine[:port]' - feature is on - engine assumes the proxy is deployed on
    itself. port is optional, default is 6080.
 - host_fqdn_or_ip:port - feature is on, engine then assumes that the
   proxy is deployed on the machine specified by host_fqdn_or_ip:port.

Things changed against last patchset:
 - switched to plain ws protocol (only until the certificate creation is
   integrated!)
 - enabled logs for websockify

Things to be done:
 - generating certificate for tls communication between proxy and client
 - testing

Change-Id: I44e9870b88537360a1886e89c08f18865eae2ef0
Signed-off-by: Frantisek Kobzik <fkobzik@redhat.com>
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=838468