App: harmonize API of App::Application

* make getHomePath() static and return a std::string
* make getExecutableName() static and return a std::string

src/Gui/WidgetFactory.cpp

@@ -431,7 +431,7 @@ void PyResource::load(const char* name)
     // checks whether it's a relative path
     if (fi.isRelative()) {
         QString cwd = QDir::currentPath ();
-        QString home= QDir(QString::fromUtf8(App::GetApplication().getHomePath())).path();
+        QString home= QDir(QString::fromStdString(App::Application::getHomePath())).path();
 
         // search in cwd and home path for the file
         //