Creates one or more contributors in the project.
Requires Manage contributors admin right. If is_admin flag is set to true,
the user would automatically get access to all project languages,
overriding supplied languages object. Attribute fullname will be ignored,
if the user has already been registered in Lokalise.
Updates the properties of a contributor. Requires Manage contributors admin right.
If you want to give an existing contributor access to a new language,
you must specify full languages array, including the previously added languages as well.
IContributors
You may add unlimited number of contributors to your project. User roles include admin, translator and reviewer.