Update kimchi.config values according to command line input

Kimchi allows users to change some configuration values by command line.
Those values override the kimchi.conf values.
That way we need to properly update kimchi.config.config to provide the
accurate data for whole application.

Signed-off-by: Aline Manera <alinefm@linux.vnet.ibm.com>
Delete http_port from /config API as it is not in use anymore

http_port information was used to display the guest console
But since we have changed how to redirect user to guest console by adding
the ui/pages/websockify/console.html it is not in use anymore.
So remove it.

Signed-off-by: Aline Manera <alinefm@linux.vnet.ibm.com>
Add federation option to Kimchi config file

It is also allows user to enable/disable the federation feature by the
command line:

kimchid --federation=[on|off]

The default value is: off which means the federation feature will be
disabled

Signed-off-by: Aline Manera <alinefm@linux.vnet.ibm.com>
Discover Kimchi peers using openSLP

When federation feature is enabled, Kimchi server will be registered
on openSLP service on server starting up. It will expose the Kimchi URL
to others Kimchi peers.

To discover Kimchi peers in the same network, the following API is provided:

GET /peers
[
    https://ubuntu-vm:8001,
    https://rhel-vm:8001
]

Signed-off-by: Aline Manera <alinefm@linux.vnet.ibm.com>
Add documentation on how to enable federation on Kimchi

README-federation.md is specific for the federation feature.
It explains how to install openSLP and enable federation on Kimchi.

Signed-off-by: Aline Manera <alinefm@linux.vnet.ibm.com>
Expose federation on /config/capabilities

That way we can properly update the UI when federation is enabled or not

Signed-off-by: Aline Manera <alinefm@linux.vnet.ibm.com>