Give admins the ability to mark a project as 'open'

[vanessuniq]

Currently all project are private. Having the ability to mark a project as open will ease external collaboration.
An open project will automatically give all vulcan user viewer access. Then a user can request access to collaborate on an open project (author role)

Tasks

• Admin should be able to change the visibility of a project
• vulcan user can request access to an open project