* `-e [REDACTED]` → `-e SOME_SECRET=[REDACTED]`
* Replaces `Utils.redact` with `Utils.sensitive` to clarify that we're
indicating redactability, not actually performing redaction.
* Redacts from YAML output, including `mrsk config` (fixes#96)
Allow the hosts for accessories to be specified by host or role, or on
all app hosts by setting `daemon: true`.
```
# Single host
mysql:
host: 1.1.1.1
# Multiple hosts
redis:
hosts:
- 1.1.1.1
- 1.1.1.2
# By role
monitoring:
roles:
- web
- jobs
```
