[*] BO : add class on TD in standard List

Back office :
Add a class on TD in list created by getList()
In fields_list array of AdminController, we can add a new parameter('class')

example :
		'name' => array(
			'title' => $this->l('Name'),
			'width' => 150,
			'class' => 'ma_classe',
			'filter_key' => 'b!name'
		),
This parameter can be used for javascript effect, ...

Thanks.
Merge pull request #968 from ccauw/patch-12

[*] BO : add class on TD in standard List