Fix metaclasses support in recent pylint versions
Fix metaclasses support in recent pylint versions

Recent versions of pylint require the first parameter of a metaclass to be
"cls". Older versions want "mcs". There's no way to support both by changing the
code, so the configuration file of pylint is changed instead, to have the
current codebase work with both versions.

Signed-off-by: Michele Tartara <05f7077a2c6cbbdc4af4ba42e3ef89a0df846179@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

mbakke/ganeti,mbakke/ganeti,ganeti/ganeti,leshchevds/ganeti,apyrgio/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,leshchevds/ganeti,apyrgio/snf-ganeti,grnet/snf-ganeti,apyrgio/ganeti,mbakke/ganeti,ganeti/ganeti,onponomarev/ganeti,leshchevds/ganeti,andir/ganeti,andir/ganeti,dimara/ganeti,yiannist/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,dimara/ganeti,apyrgio/snf-ganeti,ganeti/ganeti,bitemyapp/ganeti,yiannist/ganeti