JsonWizard: Small code cleanup on summary page

Use constants for strings, simplify signal handling a bit

Change-Id: I80f2985c8e75e98d5f1638626f21c2d9c2efac9c
Reviewed-by: Alessandro Portale <alessandro.portale@theqtcompany.com>

src/plugins/projectexplorer/jsonwizard/jsonsummarypage.h

@@ -55,8 +55,7 @@ public:
 public slots:
     void triggerCommit(const JsonWizard::GeneratorFiles &files);
     void addToProject(const JsonWizard::GeneratorFiles &files);
-    void projectNodeHasChanged();
-    void versionControlHasChanged();
+    void summarySettingsHaveChanged();
 
 private:
     void updateFileList();