Add a function to enable AF status without changing defined filters.
Add a CanBus attribute to set overall status of acceptance filters.

Fixed #236.
Merge branch 'next' into 236-restore-af-control

Conflicts:
	script/bootstrap/pip-requirements.txt
Merge branch 'next' into 236-restore-af-control
Fix check on LPC17xx for if AF should be bypassed or not.
Switch back to 'next' branch of openxc-python, changes are merged.