Enable some off-by-default checks
Enable some off-by-default checks

Some of the available checks are disabled by default, like:
[H106] Don’t put vim configuration in source files
[H203] Use assertIs(Not)None to check for None

Change-Id: I3854538ff6e144f88d4f0e8894573298da53869d

openstack/ec2-api,stackforge/ec2-api,stackforge/ec2-api,openstack/ec2-api