Display the number of pending jobs on the Queue manager page.

Problem/Motivation

It is necessary to get real data from Redis about pending jobs.

Steps to reproduce

1) Fill in the queue.
2) Go to the Queue manager page /admin/config/system/queue-ui. The counter should display the number of items
3) The count should display the number of pending jobs but display "0" at all.

Proposed resolution

Update method numberOfItems in the ResqueQueue.php class for correct displaying.