engine.configure(): Fix order of operations during config update

Ensure that 'stop' actions are executed before 'start' actions.

Otherwise there can be problems where a new app and an old app both
want to use the same resource and the new app starts before the old
one has terminated. For example, when replacing an app like intel10g
that needs exclusive use of a PCI device.
[intel10g, pci] Exclusively lock PCI devices before use

This is to prevent two snabb processes from attempting to control the
same PCI device at the same time, which could lead to... hilarity.

This change also involves an explicit close operation on the PCI
device when the intel app is stopped.
[lib.nfv.config] More verbose debug output in selftest