Show # of Associated Users in Delete Confirmation Popup

Purpose: To augment confirmation modal when deleting permission sets to include information about how many users are associated with the permission set so that administrators can make better decisions about what they should/shouldn't delete.

Scenarios:

1. Scenario
   • Given the Delete button/icon on Settings > Users > Permission sets
   • When clicked
   • Then a modal will pop up asking user to confirm the deletion or cancel the deletion similar to what's shown here: https://drive.google.com/file/d/0By8ccf5VV4EWZkRSVXc2cE1IbmM/view?usp=sharing
     • Header: Delete permission set? CB: Please use sentence case, despite the title case used in the mock-ups
     • Body: The permission set <permissionSetName> will be removed from permission sets and disassociated from <N> users.
     • Buttons: Cancel, Delete