Various bug fixes while running tests on this branch in the octo lab.

Various bug fixes while running tests on this branch in the octo lab.

Made YamlConfig work more closely like a dictionary by extending
collections.MutableMapping.  It still needs some work to be able to be
used interchangeably with a dict - most noteably with yaml.safe_dump.

Decided to just use a dict instead of JobConfig for args['<config>'].
Too many other codepaths are assuming that config is a dict.

Signed-off-by: Andrew Schoen <aschoen@redhat.com>