Add pretend_min_part_hours_passed before rebalance

Add pretend_min_part_hours_passed before rebalancing swift ring.
Make sure some dirs are created with proper ownership.

Closes-bug: #1402701
Change-Id: Id49a6ee1852e5d65a9994802c5949eac26dc1821
Merge "Add pretend_min_part_hours_passed before rebalance" into stable/6.0