Spice proxy enable/disable based on source ip.

Issue

• We will be using a reverse proxy to connect the spice client
• At this time, when we enable the SpiceProxyDefault setting in the manager, all connections are redirected through the proxy by default.
• Users can prevent this by deselecting the "Enable SPICE Proxy" in the UserPortal.
• Default setting is enabled.
• We would like to see the following:
  1. The ability to have the proxy selected by source ip address. This way the end-user does not have to select anything, as the connection would just work.
  2. If there is a default setting for the user portal, at least it should be configurable. In our case, most users would connect without a proxy, so disabled by default would make much more sense.