Backport labels added to issues

[Lasse Karstensen]

Hi all.

I've created some new labels in varnishcache/varnish-cache/ now.
They are:

    backport-review-4.0
    backport-review-4.1
    needs-backport-4.0
    needs-backport-4.1


When a issue is closed (minus exceptions, see below) the backport-review-nnn
labels will be added automatically.

After the backport team has reviewed it, the label will be removed from the (still closed) issue.

If the bug doesn't apply to the version, we are done and can forget about it for now. If it
needs a backport, the "needs-backport-nnn" label will be added manually. When it is commited, that
label is removed manually.

A issue will not receive backport labeling if it has "duplicate" or "packaging". We'll extend this
as we get more experience on the false positives.

-- 
Lasse Karstensen
Varnish Software AS