Support configure get/set with nested attrs

This only works with the full qualified name, i.e.
with the profile specified.  For example:

    # Works:
    aws configure set default.s3.signature_version s3v4
    aws configure get default.s3.signature_version s3v4
    aws configure set profile.prod.s3.signature_version s3v4
    aws configure get profile.prod.s3.signature_version s3v4

    # Does not work
    aws configure set s3.signature_version s3v4
    aws configure get s3.signature_version s3v4
May need to rethink the approach.  I've left a failing test
to make it easy to pick right up.
Merge branch 'configure-set-nested' into develop

* configure-set-nested:
  Support configure get/set with nested attrs
Update changelog with latest changes
Update tests to work with expect-100 bcore branch
Merge branch 'EronHennessey-doc_updates' into develop

* EronHennessey-doc_updates:
  many more example updates from the aws doc team
  Merged with doc team repository.
Remove smart quotes from autoscaling example
Merge branch 'EronHennessey-doc_updates' into develop

* EronHennessey-doc_updates:
  Remove smart quotes from autoscaling example
removed tab chars from a topic, and removed a bad link from another