Simplify archetype.childNodePathBase method

[ppazos]

In Archetype there are two methods to handle paths. Looking at each one, it seems childNodePathBase could return just path().

public String parentNodePath() {

    // remove both "/"  and attribute name
    return path().substring(0, path().length() - rmAttributeName.length() - 1);
}

public String childNodePathBase() {
    return parentNodePath() + PATH_SEPARATOR + rmAttributeName;
}