factory.js
function (namespaces) {
    _.forEach(namespaces, function (level, namespace) {
      cache.add(namespace, level);
    });
    return this;
  }
function (namespaces) {
    _.forEach(namespaces, function (level, namespace) {
      cache.add(namespace, level);
    });
    return this;
  }
function ( namespaces ) { _ . forEach ( namespaces , function ( level , namespace ) { cache . add ( namespace , level ) ; } ) ; return this ; }
set the namespaces configuration.

Config object
```
{
'root': 'all',
'namespace1.namespace2': 'info',
}
```

**root** namespace is for all unknown namespaces.

@param {object} namespaces the map with the namespace and its log level
@return {self}
set the namespaces configuration .