Request: RawNetworkInterfaceDriver: add dhclient control and non-NetworkManager dnsmasq info functions

[pmelange]

It would be nice to have the ability to control dhclient on the exporter's NetworkInterface resource to release a lease and to renew a lease. Adding this functionality to the RawNetworkInterfaceDriver makes more sense since the NetworkInterfaceDriver seems to be focused only on NetworkManager (sic) control.

suggested method names could be:
RawNetworkInterfaceDriver.dhclient_release()
RawNetworkInterfaceDriver.dhclient_renew()

Additionally, the NetworkInterfaceDriver has the ability to get a list of the NetworkManager controlled dnsmasq leases. For systems not using NetworkManager (sic), a similar method for RawNetworkInterface would be nice to have. The method could assume that /etc/dnsmasq.conf is the config file and check it for the attribute dhcp-leasefile which if unset defaults to /var/lib/misc/dnsmasq.leases reference. Also, the location of the dnsmasq.conf file could be a new attribute to RawNetworkInterfaceDriver.

suggested method name could be:
RawNetworkInterfaceDriver.get_dhcpd_leases()