registering multi-mdoel-directory

The tiny changes that has been made now every the programmer is able to set multi-model-directory

for example every time that developer call the following function at \ActiveRecord\Config::initialize(function($cfg){}) function :

+ $cfg->set_model_directory($another_db_model_path);

the $another_db_model_path will be added to model directory string and in autoloading this directory will be consider when trying to locate mdoles' directory

NOTE: this comes realy helpfull when developers are working with multi module application and in modules they get access and use other modules' Models too.