add missing calls to base.OnActivityResult() in *EditActivity, leading to errors saving with YubiChallenge (#4).

src/keepass2android/EntryEditActivity.cs

@@ -713,6 +713,7 @@ namespace keepass2android
 		
 		protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
 		{
+		    base.OnActivityResult(requestCode, resultCode, data);
 			switch (resultCode)
 			{
 			case (Result)ResultOkIconPicker:

src/keepass2android/GroupEditActivity.cs

@@ -144,7 +144,8 @@ namespace keepass2android
 		
 		protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
 		{
-			switch ((int)resultCode)
+		    base.OnActivityResult(requestCode, resultCode, data);
+            switch ((int)resultCode)
 			{
 				case EntryEditActivity.ResultOkIconPicker:
 					_selectedIconId = data.Extras.GetInt(IconPickerActivity.KeyIconId, (int) PwIcon.Key);