Fix partially ignored checks
Fix partially ignored checks

When a check has only a subset of its
codes requested to be ignored we need
to make sure when we run that check that
we still skip the codes that were requested
to be ignored (and let the ones that were
not requested passthrough).

Change-Id: I05f419a8d99fa0cd9cea50e264e2a4c4a64376bd

tschuy/doc8,doismellburning/doc8,openstack/doc8,stackforge/doc8