update to release 0.2.21
- fix: crash when ethtool advertised modes in unknown format (#689715)
- fix: check if ELEVATOR_KTUNE_DEVS is set
- typo fix: scomes, pooling -> polling
- fix: handle exceptions when determining type of network device (#707079)
- remove hal-disable-polling as HAL is being removed from Fedora (#710920)
- fix: add LSB headers to ktune initscript not to cause deadlock in systemd (#690177)
- fix: incorrect handling of stdin/stdout/stderr during daemon creation (#695480)