Get Plugins for a single site
function( site ) {
		if ( ! site ) {
			return [];
		}
		if ( ! _pluginsBySite[ site.ID ] && ! _fetching[ site.ID ] ) {
			PluginsActions.fetchSitePlugins( site );
			_fetching[ site.ID ] = true;
		}
		if ( ! _pluginsBySite[ site.ID ] ) {
			return _pluginsBySite[ site.ID ];
		}
		return values( _pluginsBySite[ site.ID ] );
	}