Testability

Adds a public init to FacebookAuth.Result to allow host applications to better mock the authenticate method.

Permissions

Adds the ability to specify permissions when calling authenticate and adds the granted permissions to the result. It also adds a new ask(for: permissions) method to request previously declined permissions.

Optimizations

Breaking
Removes the viewController argument from the FacebookAuth initializer.

Initial release

Adds the most basic implementation of Facebook authentication.