Add support for bonding options system prio, port key and actor system mac. These options exist in the linux kernel since 4.2 (torvalds/linux@171a42c38c) Details: https://www.kernel.org/doc/Documentation/networking/bonding.txt
This suppress the following warnings: ``` Warning: Stopping systemd-networkd.service, but it can still be activated by: systemd-networkd.socket ```