rename certify_key_item to the more appropriate multi_certify_item

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/adapter/MultiUserIdsAdapter.java

@@ -67,7 +67,7 @@ public class MultiUserIdsAdapter extends CursorAdapter {
 
     @Override
     public View newView(Context context, Cursor cursor, ViewGroup parent) {
-        return mInflater.inflate(R.layout.certify_key_item, null);
+        return mInflater.inflate(R.layout.multi_certify_item, null);
     }
 
     @Override