ethtool_options vdsm hook
=================================
This hook allows the user to set ethtool options for networks that are set
over network interface cards (directly or indirectly).

Requirements:
* oVirt-3.5

Usage:
In the oVirt UI edit custom network properties and, for the key 'ethtool_opts'
set the command line parameters that one would pass to the ethtool command
line application. E.g.:
    '--coalesce ethX rx-usecs 14 sample-interval 3 --offload ethX rx on lro on tso off --change ethX speed 1000 duplex half'

Note that it is possible to substitute the ethX name of the NIC with a '*' and
the hook will fill in the right nic name for you.

bonding
--------
For bondings there are two options:
a) Pick which devices to apply something on (subject to the command actually
   being appliable with a single ethtool call):
   If it is for a bond with em1 and em2, it could look like:
    '--offload em2 rx on --offload em1 tx on'
b) Apply to all the bond slaves:
    '--coalesce * rx-usecs 14 sample_interval 3'
   This would execute an ethtool process for each slave.