stop-edgex.sh script generates lots of apparmor denials

[tonyespy]

The current edgex-core snap (0.5.1+cali-20180322) stop script generates lots of AppArmor denials due to its use of the 'ps' command.

Adding the interfaces system-observe (auto-connectable) and process-control should get rid of most of these denials.

Tested on an Ubuntu 16.04 LTS Desktop system.

[tonyespy]

Note, adding plugs: [system-observe, process-control] gets rid of all but three AppArmor denials for stop-edgex.sh for "operation=capable".

[tonyespy]

And what I think now may be a regression is that when the stop-script now throws an error when it tries to kill device-virtual using "kill". The process-control interface is connected, and I'm pretty sure this previously worked. Here's the error generated:

+ kill_service 24463 device-virtual
+ echo sending SIGKILL to device-virtual (24463) service
sending SIGKILL to device-virtual (24463) service
+ kill -9 24463
/snap/edgexfoundry-core/x24/bin/stop-edgex.sh: 10: kill: Operation not permitted

This was the lazy way to take down the JRE, we may need to investigate whether or not java will exit in response to other signals.

Snap version: 0.5.2+cali-20180612 x24 run on Ubuntu 16.04 LTS running core snap 16-2.32.8 4650.

[tonyespy]

Hmmm, looks 'sudo' fixes the afore-mentioned problem with 'kill'. duh.