Handle a list of strings from a dict in text output

This situation comes up in commands such as
`aws elb describe-load-balancers`.  The output
now looks as expected (note the "us-west-2b")

Before:
```
AVAILABILITYZONES	us-west-2a
HEALTHCHECK	10	30	HTTP:80/index.html	5	2
LISTENER	80	HTTP	80	HTTP
SOURCESECURITYGROUP	amazon-elb-sg	amazon-elb
LOADBALANCERDESCRIPTIONS		a	b	c	d
us-west-2b
```

Now:
```
AVAILABILITYZONES	us-west-2a
HEALTHCHECK	10	30	HTTP:80/index.html	5	2
LISTENER	80	HTTP	80	HTTP
SOURCESECURITYGROUP	amazon-elb-sg	amazon-elb
LOADBALANCERDESCRIPTIONS		a	b	c	d
AVAILABILITYZONES	us-west-2b
```

See: https://forums.aws.amazon.com/thread.jspa?threadID=140646