Add scope support to Model::relations()

Enhancement patch submitted: http://code.google.com/p/yii/issues/detail?id=2029

This is a patch to add a new parameter to Model::relations() arrays. (actually, CActiveRecord::relations() )

i.e. - ‘scopes’=>‘scope1:scope2:scope3’ OR ‘scopes’=>array(‘scope1’,‘scope2’,‘scope3’)

The thought is so we can specify relations that always use predefined scopes.

I’ve tested this patch, I’ve found no negative side-effects.