Can't use -pk/-pc with k8s audit rules

[mstemm]

If you try to run falco 0.13.0 with -pk/-pc, falco won't start:

Wed Nov 14 01:12:58 2018: Runtime error: Error loading rules: [string "-- Copyright (C) 2016-2018 Draios Inc dba Sys..."]:520: Invalid output format 'K8s Operation performed by user not in allowed list of users (user=%ka.user.name target=%ka.target.name/%ka.target.resource verb=%ka.verb uri=%ka.uri resp=%ka.response.code) k8s.pod=%k8s.pod.name container=%container.id': 'Could not parse format string "K8s Operation performed by user not in allowed list of users (user=%ka.user.name target=%ka.target.name/%ka.target.resource verb=%ka.verb uri=%ka.uri resp=%ka.response.code) k8s.pod=%k8s.pod.name container=%container.id": unknown filtercheck field k8s.pod.name container=%container.id'. Exiting.

The problem is that -pk/-pc add an implicit %container.info to the output of every rule. It should only do that for source=syscall rules.

[mfdii]

fixed in #495