This commit adds the feature to change offloads for nics.

This commit adds the feature to change offloads for nics.
Currently GRO, LRO GSO, TSO, UFO, TX and RX Offload are supported.

One can read the current value with ethtool -k NICNAME.
Values are set with ethtool -K NICNAME gro on lro on gso on tso on ufo on tx on rx on

An example for the config file is:

iface eth0 static
	gro-offload no

The default value will be kept in the statemanager. The default value might differ depending on the NIC and is saved upon the first change.