virt: github report set cache expiry by class

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: github report add issue description key

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: github report cache repo labels

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: github report support modifying issues

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: github report label unlabled issues

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: github report pylint cleanup/fixes

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: github report on least updated pull requests

Signed-off-by: Chris Evich <cevich@redhat.com>