Fix typos, quote error messages in logs

I took all the spots where the package was logging `err=%s` and replaced with `err=%q` since golang error messages tend to have spaces. Also added a missing verb to a log format string which was generating the following log (note the junk at the end):

```
2014/11/24 16:19:42 component=FSM name=instance_launch at=error error=decision-execution-error err="panic in decider, capture error state" state=wait_for_boot next-state=%!(NOVERB)%!(EXTRA string=wait_for_boot)
```