get_post_class() do not set 'sticky' class in administration posts table

[corsonr]

get_post_class() does set a 'sticky' class to sticky post on the frontend but not in the administration. So, there's no way to differentiate a sticky post from another non-sticky post excepted the span element to its right.

Adding something similar to this fix the problem:

	// sticky for Sticky Posts in administration
	if ( is_sticky($post->ID) && is_admin() )
		$classes[] = 'post-sticky';