Plucks the value of a property from each item in the Array. Example:

Ext.Array.pluck(Ext.query("p"), "className"); // [el1.className, el2.className, ..., elN.className]

@param {Array/NodeList} array The Array of items to pluck the value from.
@param {String} propertyName The property name to pluck from each element.
@return {Array} The value from each item in the Array.
function(array, propertyName) {
            var ret = [],
                i, ln, item;

            for (i = 0, ln = array.length; i < ln; i++) {
                item = array[i];

                ret.push(item[propertyName]);
            }

            return ret;
        }