allocate_net vdsm hook
=====================
This hook allocates a random network to a VM when the VM is started.

This hook is useful in cases where one has a set of equivalent networks, and
wants to distribute VMs evenly among them, so the networks share the traffic
load.
The more VMs allocated with networks, the tendency of VMs to be evenly
distributed among networks rise.

Installation:
* Use engine-config to set the appropriate custom properties as such:

Custom property for a specific vNIC profile:
    sudo engine-config -s CustomDeviceProperties="{type=interface;prop={equivnets=\s*(\S+)(\s*\S+)*}}"
    sudo service ovirt-engine restart

* Verify that the custom properties were added properly:
    sudo engine-config -g CustomDeviceProperties

Usage:
Create a 'meta network'. Add to it a vNic profile that contains the extra
property named 'equivnets' (as defined above) and input a whitespace separated
list of network names as the network pool.

If a VM is configured to use this network profile, it will be connected to a
random network from the defined pool once powered on.

# note that all the networks defined in the whitespace separated list should be
configured on all the hosts on which VMs are planned run.