Merge pull request #170 from Azure-Samples/yuanyang

[Face] Fix Face build failing

Author: yangyuan

samples/Face/Program.cs

@@ -19,7 +19,7 @@ static void Main(string[] args)
             FindSimilarInLargeFaceList.Run(endpoint, subscriptionKey).Wait();
 
             // Group sample.
-            Group.Run(endpoint, apiKey).Wait();
+            Group.Run(endpoint, subscriptionKey).Wait();
 
             // Identify sample.
             IdentifyInPersonGroup.Run(endpoint, subscriptionKey).Wait();