Delete unused testenv:checkconfig in tox
Delete unused testenv:checkconfig in tox

The testenv:checkconfig is unused and there is not the file
{toxinidir}/tools/config/check_uptodate.sh in cloudkitty.

Change-Id: Ifa8293a7b04557316c7256519b8821b5a668c554

stackforge/cloudkitty,stackforge/cloudkitty,openstack/cloudkitty,openstack/cloudkitty