Investigate and fix service and timer leaks.

[joeysk2012]

There are still issues with service and timer leaks when udev rules fail or the unit exits on code 1 for some reason.
This could lead to extra policy-routes@.service or refresh-policy-routes@.timer to remain on the system after the interface has been deleted. policy-routes@.service should no longer be running but rather remain because RemainAfterExit=yes. Leaked refresh-policy-routes@.timer are more sinister because they can process every 60 seconds if not disabled or stopped.

[ddermendzhiev]

Can you provide more details on the scenarios in which you observed the leaks?

[ddermendzhiev]

Also, is there a spec for these units that defines their expected lifecycle? Should units be automatically cleaned up when the iface is removed, even if the udev remove rule fails?

[ddermendzhiev]

For context: #149