It's pick up of [Gabriel's work] (https://lab.nexedi.com/gabriel/slapos/tree/caucase_integration) with updates of caucase egg and other fixes.

Tasks:

• use CA from caucase !506 (comment 73495)
• update ports !506 (comment 73501)
• improve readme !506 (comment 73503) and !506 (comment 73504)
• check environment passing !506 (comment 73505)
• check which fixes from !434 (merged) apply immediately
• wait for merge of erp5!829 (merged)