Missing 'maintainers' array values for per-project permissions

[ghost]

project_user_access() checks if a user is listed as a maintainer of a project in order to grant them access, however this check is the only place the string 'maintainers' is used in the module. This list isn't created anywhere, and so access doesn't get granted.

This check either needs to be removed/changed, or the 'maintainers' list/functionality added...

[quicksketch]

The only permission we have currently is the site-wide "administer projects" permission, which works properly.