Spaces with no manager

[jesmrec]

Describe the bug

An space should always have at least one manager. There is a way to force an space to have no managers.

Steps to reproduce

1. In a space, set two managers
2. Set expiration date for both
3. Turn one of the managers into another role (editor or viewer), so, there is only one manager, who keeps the expiration date set in step 2.
4. Wait till the expiration date is due

Expected behavior

Several options:

• manager should stay as manager, ignoring the expiration date
• any other user is assigned as new manager as the existing one is removed from the space
• expiration dates do not apply to the manager role if there are no other manager in the space

Spaces always have at least one manager.

Actual behavior

no managers in the space, because the only one was out because the expiration date was due

Setup

[jvillafanez]

owncloud/reva#452 should fix the issue. Next reva bump should include the fix.