Panic when auditctl not found

[diogomonica]

This should probably not give a runtime panic, and should just skip the tests.

➜  ./main -f default.toml 
2016/05/10 12:14:17 Running Audit: Host Configuration
[WARN] - 1.1 Create a separate partition for containers 
     Containers NOT in seperate partition

[PASS] - 1.2 Use the updated Linux Kernel 
[INFO] - 1.4 Remove all non-essential services from the host 
     Host listening on 29 ports: [4371 57621 53 17500 4381 17600 17603 47856 48516 44692 33926 59646 42908 35872 54582 44670 53846 34510 36274 52994 37242 53816 52452 39380 42390 35768 39618 56460 37950]

[PASS] - 1.5 Keep Docker up to date 
[INFO] - 1.6 Only allow trusted users to control Docker daemon 
     The following users control the Docker daemon: [diogo]

2016/05/10 12:14:18 Could not find auditctl tool
panic: Could not find auditctl tool

goroutine 1 [running]:
panic(0x7afe00, 0xc8204de500)
    /usr/lib/go-1.6/src/runtime/panic.go:464 +0x3e6
log.Panicf(0x95b2c0, 0x1c, 0x0, 0x0, 0x0)
    /usr/lib/go-1.6/src/log/log.go:327 +0xd8
github.com/diogomonica/actuary/checks.checkAuditRule(0x8ff2b0, 0xf, 0xc8204f1d10)
    /home/diogo/go/src/github.com/diogomonica/actuary/checks/checks.go:250 +0x308
github.com/diogomonica/actuary/checks.AuditDockerDaemon(0xc8200f2120, 0x945ef0, 0x17, 0x0, 0x0, 0x0, 0x0)
    /home/diogo/go/src/github.com/diogomonica/actuary/checks/dockerhost.go:139 +0x85
main.main()
    /home/diogo/go/src/github.com/diogomonica/actuary/cmd/actuary/main.go:67 +0x57e

[zuBux]

Yup, I added some extra code to just skip tests if conditions are not met (e.g no Container Runtime checks when no containers running). I probably missed that, will get fixed asap

[diogomonica]

Cool, make sure to close it on the PR.