function addWelcomeProjectPath(path) {
        var welcomeProjects = ProjectModel._addWelcomeProjectPath(path,
                                                                 PreferencesManager.getViewState("welcomeProjects"));
        PreferencesManager.setViewState("welcomeProjects", welcomeProjects);
    }
Adds the path to the list of welcome projects we've ever seen, if not on the list already.

@param {string} path Path to possibly add