Periodicity calculation should only be based on Hosting Subscription
periodicity, and not hardcoded in a script.

Limit as possible number of modifications on open order line.

Subscription start date should be based on beginning of the slap workflow, to
ensure compatibility with old data.

Use the state value only.
Correctly handle destroyed subscription which has never been associated to an
open order.

Excuse to force-run slapos test suite.

Try to reduce the number of documents created.
Always set a stop date on the open order line.

Fetching 1 element is faster than counting all.

Ensure that computer can destroy the software.

Also commit test skeleton.

Mainly give access for group/company to Hosting Subscription and its module.

As explicit is better then implicit give explicitly group/company access to
other modules and portal types even if access was already given by role/member.

Also use typical owner (zope) instead of artificial ones (admin or
ERP5TypeTestCase).