nymms should gracefully fail without permissions

I wanted to check out the ami! It looks pretty cool - only I hadn't set up an IAM profile yet and I noticed in syslog this:

```

Oct 18 23:07:19 ip-10-20-242-215 kernel: [9675236.422718] init: nymms-scheduler main process ended, respawning
Oct 18 23:07:19 ip-10-20-242-215 kernel: [9675236.890671] init: nymms-reactor main process (12129) terminated with status 1
Oct 18 23:07:19 ip-10-20-242-215 kernel: [9675236.890734] init: nymms-reactor main process ended, respawning
Oct 18 23:07:20 ip-10-20-242-215 kernel: [9675237.036472] init: nymms-probe main process (12130) terminated with status 1

```

it seems like it'd be an easy fix to have nymms fail a bit more gracefully if it doesn't have permissions to do what it needs to do.

Start by tracing the startup paths for nymms-scheduler, nymms-reactor, and nymms-probe, then reproduce the missing-IAM-permissions condition described in the syslog. Determine where the permission failure is handled and verify that the services stop or report the problem clearly instead of repeatedly terminating and respawning.

Written by the indexing model from the issue text.