add more options to create user

[iexos]

Add all options for user creation as in https://docs.nextcloud.com/server/14/admin_manual/configuration_user/instruction_set_for_users.html#add-a-new-user

This is required to be able to send welcome mails without setting a password.

It was necessary to switch post requests to send json, as python requests apparently cannot handle arrays with content-type x-www-form-urlencoded

[iexos]

switching to json posting seems to break stuff :( any idea how to solve this?

[scrutinizer-notifier]

The inspection completed: No new issues

[iexos]

close in favor of #51 (it was a stupid idea to use master branch for PR origin)