Use KeDiFa to store keys, and transmit the url to the requester for master
and slave partitions.

Download keys on the slave partitions level.

Context, nicely filled in by slapos.recipe.template, is required in the macros.

Jerome Perrin:

Update stack/caucase/README.rst

/reviewed-on nexedi/slapos!418

/reviewed-on nexedi/slapos!414

These are totally unrelated changes which were not meant to be pushed,
sorry.

Runner exporter failed with this message while checking if file changed during backup of instances files:

    < 3226bab4cd318d30cfbde18e6530435dcae3205f94103384ce266c3c73d1afeb  ./runner/instance/slappart2/srv/backup/pbs/slaprunner-slappart1-runner-1/backup.signature
    < 3226bab4cd318d30cfbde18e6530435dcae3205f94103384ce266c3c73d1afeb  ./runner/instance/slappart3/srv/backup/runner/backup.signature
    < 3226bab4cd318d30cfbde18e6530435dcae3205f94103384ce266c3c73d1afeb  ./runner/instance/slappart5/srv/backup/runner/backup.signature
    5248d5244
    < bb3d96876d1d6cecee9878d835e7515215fc5d2a6ae6b647d0e7915c36700b54  ./runner/instance/slappart4/srv/backup/runner/backup.signature
    ERROR: Some backups are not consistent, exporter should be re-run.

This is because instance in webrunner has also backup.signature the file is excluded while doing sha256sum on backup file:

    find -type f ! -name backup.signature -print0 | xargs -0 sha256sum | sort -k 66 > backup.signature

A fix is to exclude backup.signature in `find`.

If instance/slappartXX is not a folder but file, skip chdir else import/export fail with a message like:

    /srv/slapgrid/slappart18/bin/runner-exporter run at : Thu Oct  4 04:30:03 CEST 2018
    Traceback (most recent call last):
      File "<stdin>", line 17, in <module>
    OSError: [Errno 20] Not a directory: '/srv/slapgrid/slappart18/srv//runner/instance/slappart5-mariadb.dump.sql.gz'

This reverts commit 80673c8c.

All testnodes should have been updated by now, so this commit is no
longer needed.

/reviewed-on nexedi/slapos!419

/reviewed-on nexedi/slapos!416

/reviewed-on nexedi/slapos!415

/reviewed-on nexedi/slapos!408

isp data is from https://www.whoismyisp.org/ip
cn-t for china telecom, default one if isp is other value
cn-m for china mobile
cn-u for china unicom

fix rst syntax - second try

fix markdown syntax

from nexedi/slapos!408 (comment 66703)

as always, using wrapper is easier and more flexible

also use a real bash and not busybox

   bzip.org don't exist anymore, download from fosseis is ok as the md5sum guarantee we still get the same file.

/reviewed-on nexedi/slapos!406