Make space admins discoverable to a user

I just hit this issue a few mins ago:

1. Need to delete a page on the integration space
2. Realised I don't have access
3. So I need to contact space admin... so I ask Shihab, thinking he is space admin .. and he isn't... so I ask around - a few people don't know who is...
4. My solution: Have to talk to IT and ask them to tell me who is admin, then I sort my problem out.

Customers have solved this manually by:

1. Creating a page that actas like a "space directory"
2. For every space, they manually use the User List Macro to render all the users in the respective space-admin group.

Goal: Make it easy to discover who the space admins are for a space

This is the exact same model as the JIRA project listing - you can see who the admin is (And contact them manually) if you have an issue. To do this, we should:

• Add a "Space Administrator(s)" column to the space directory that lists the names of users (we can set a hard-limit to the number and do a ... if there are heaps.
• In Browse > Advanced also add the space admins here with the other space metadata.