Bugfix: Reword Delete Role for single match

Adjusts the wording and appearance of the Delete Role page to account
for instances when only a single user story is affected by the deletion.
Bugfix: Skip Delete Role forms when 0 matches

If there are 0 affected stories, delete the Role without prompting the
user for additional information.
Bugfix: Adjust appearance of Role Delete forms

If there is only a single affected story, adjust the wording and hide
the option to assign individually.

If there are no affected stories, skip the form and just perform the
delete operation.

closes #21