Add sample config check to tox pep8 job

This commit takes the check_uptodate.sh script from nova and adds it
to the pep8 tox job. This will enforce that the sample config file is
up to date for each proposed commit. This also ensures that config
options are setup properly and that the style in the sample config is
consistent because it's auto-generated.

Partially Implements: blueprint config-cleanup

Change-Id: I9efaa9fc1cf09e95d7111b000895c7b49705713b
Merge "Add sample config check to tox pep8 job"