Fix nullpointer, remove unused window feature

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/ViewKeyActivity.java

@@ -103,7 +103,6 @@ public class ViewKeyActivity extends ActionBarActivity implements
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
-        supportRequestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
         super.onCreate(savedInstanceState);
 
         mExportHelper = new ExportHelper(this);