JS boilerplate: refactor classes to functions

[vbulant]

• refactor init/factory functions as separate modules

[janpanschab]

app.init = function(Klass, container, ...args) {
    if (container) {
        return new Klass(container, ...args);
    }
};

app.factory = function(Klass, containers, ...args) {
    return [...containers].map((container) => {
        return new Klass(container, ...args);
    });
};

app.initStatic = function(klass, container, ...args) {
    if (container) {
        return klass.init(container, ...args);
    }
};