Handle a list of strings from a dict in text output

This situation comes up in commands such as
`aws ec2 describe-load-balancers`.  The output
now looks as expected:

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

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
Merge branch 'text-output-list-string' into develop

* text-output-list-string:
  Handle a list of strings from a dict in text output
Add changelog entry for issue 516