Deallocate port before trying to delete iptables chain

Fixes #7954
Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com>
Merge pull request #7955 from LK4D4/ignore_delete_err_on_unmap_#7954

Deallocate port before trying to delete iptables chain
Fix link for configuring automated builds
TarSum: versioning

This introduces Versions for TarSum checksums.
Fixes: https://github.com/docker/docker/issues/7526

It preserves current functionality and abstracts the interface for
future flexibility of hashing algorithms. As a POC, the VersionDev
Tarsum does not include the mtime in the checksum calculation, and would
solve https://github.com/docker/docker/issues/7387 though this is not a
settled Version is subject to change until a version number is assigned.

Signed-off-by: Vincent Batts <vbatts@redhat.com>
Merge pull request #7689 from vbatts/vbatts-tarsum_versioning

TarSum: versioning
Merge pull request #7975 from passy/patch-2

Fix link for configuring automated builds