Decode list arguments to unicode

Fixes #711.
Add note about --output not being used in s3 ls
Fix test bug with utf-8 encoding
Raise exception when bad output format is given

While argparse handles the case where it's specified as an arugment,
we need to validate the case when output is specified as an env var
and a config var.
Merge branch 'bad-output-type' into develop

* bad-output-type:
  Raise exception when bad output format is given
Fix py3 bug, only decode if it's a binary type
Merge branch 'fix-list-unicode' into develop

Closes #712

* fix-list-unicode:
  Fix py3 bug, only decode if it's a binary type
  Fix test bug with utf-8 encoding
  Decode list arguments to unicode
Update changelog with latest bug fixes
Merge branch 'document-s3-output' into develop

* document-s3-output:
  Add note about --output not being used in s3 ls