Save extended attributes when creating tar

The way redhat-common's extract-image script was creating the base
tarball caused file capabilities to get dropped, which meant that
things like ping in RHEL 7 images was unusable for regular users.
This change adds the necessary options to the tar call to maintain
as many extended attributes as possible.

--acls and --selinux are intentionally omitted, and the selinux
xattrs are filtered out because all of those items cause issues
in our chroot environment.  We restore selinux attributes at the
end of the build anyway so that shouldn't be a problem.

bz reference: https://bugzilla.redhat.com/show_bug.cgi?id=1144149

Change-Id: Ibff99ce9bde01bc5ecf95dc3a5d3e2cebe5015b9
Merge "Save extended attributes when creating tar"