Remove service feedback creation URL

This functionality has now been moved over to the `support-api`.
DRY support request new forms

This change:

* makes all 'new request' forms much more uniform. There's a shared 'new' view, and all the request-specific elements are in the 'request_details' partials.
* introduces conditional logic to show guidance at the top of the form, if any is present.
Merge pull request #195 from alphagov/remove-service-feedback-posting

Remove service feedback creation URL
Merge pull request #196 from alphagov/dry-request-views

DRY support request new forms
Remove redundant heading on anonymous feedback index

Also change dev quotes to smart quotes
Move Feedex results table and paginators into partial
Anon feedback: don't display empty table

This shows a friendlier message when there's no feedback for that path
Convert page header to use the govuk_admin_template styles

This also fixes the stray border on the style guide