Add a single organiser mode

[publicarray]

Useful to prevent the public from creating Events/Organisations without authorisation. (should be enabled by default IMHO; but that would break compatibility)

I would use this where there is only one organisation publishing events and where we don't want to allow the public to create Events/Organisations

(I think this should be enabled by default IMHO; but that would break compatibility)

[ChildLearningClub]

@publicarray I actually can’t figure out how to allow the public to create events :). It appears that the admin can create users and add organizers, but I don’t see a public facing registeration page.

[publicarray]

The public can create new organisation admin accounts and organisers from /signup. from there users within the organisation can create new events.

This PR disables the /signup route after installation

[ChildLearningClub]

Thank you @publicarray, I must have missed that... I agree the ability to disable that function is a great option to have.

[etiennemarais]

@publicarray Thank you for contribution. I am loojing to get this merged into our next branch. Please help with the conflicts? 🙏 The next branch has recently undergone a large laravel version upgrade (6.5.1) Please use the new routes file since it has moved

[etiennemarais]

Please deal with the conflicts?

[publicarray]

Closing in favour of new pull request on the updated branch next #741 🤩