Add an option to force selection of save path

By default oracle saves cards.xml to the correct path, where cockatrice
will be able to pick it up;
if oracle is not able to determine the path or the user unchecks the
option, oracle will ask for a save path

oracle/src/oraclewizard.h

@@ -100,6 +100,7 @@ public:
      SaveSetsPage(QWidget *parent = 0);
 private:
      QTextEdit *messageLog;
+     QCheckBox * defaultPathCheckBox;
 protected:
      void initializePage();
      void cleanupPage();