Replace alert banner title with administrive title, add optional title field for display?

[andybroomfield]

Titles are needed for the alert banner for the admin view, and for implementing the gov.uk pattern.
However not all alerts need a title to be displayed, and sometimes the headers can be handled with the wysiwyg field.

If this change was carried forward, the change would be:

• Change the title field to Administrive Title (like blocks)
• Add a new field (Title) to the default bundled alert banner
• If the display title is blank, don't display that in the template (Remove the display title checkbox)

[willguv]

@andybroomfield good suggestion. Titles aren’t used by many, so should be optional

[andybroomfield]

This might be comming back up as an issue as BHCC new pattern removes the titles from display.
We still need a title in the admin interface though, otherwise it gets labelled as banner 1, banner 2 etc... Hard to spot in an emergency.