Fix Auth Swift sample imports to be more precise and flexible for other build environments. (#95)

Author: XiangtianDai

AuthSamples/SwiftSample/AppDelegate.swift

@@ -16,8 +16,8 @@
 
 import UIKit
 
-import FirebaseDev // FirebaseCore
-import GoogleSignIn // GoogleSignIn
+import FirebaseDev.FirebaseCore
+import GoogleSignIn
 
 @UIApplicationMain
 class AppDelegate: UIResponder, UIApplicationDelegate {

AuthSamples/SwiftSample/ViewController.swift

@@ -16,8 +16,8 @@
 
 import UIKit
 
-import FirebaseDev // FirebaseAuth
-import GoogleSignIn // GoogleSignIn
+import FirebaseDev.FirebaseAuth
+import GoogleSignIn
 
 final class ViewController: UIViewController, UITextFieldDelegate {
   /// The profile image for the currently signed-in user.