Change select boxes to radio buttons for mapping type selection

- Radio buttons make switching between types when editing a mapping
  easier. It's one click rather than 2/3, and you can see the options
  sooner. This has been a minor usability problem in user research.
- Make the radio button style consistent with the non-JS filter mappings
  radio buttons: all on one line.
Fix indentation of the Type label and radio buttons in forms
Use the existing mapping type as the selected radio button on edit

- Switch to using the Rails form helpers in one case.
Remove a reference to managed_by_transition from an import rake task

- A transtion-postgres Errbit error
  (https://errbit.preview.alphagov.co.uk/apps/53e8c4e40da115dfc200684d/problems/5425716e0da11550d7001181)
  made me do a full search
  everywhere. Clearly nothing has used this rake task since
  https://github.com/alphagov/transition/pull/413 otherwise
  Errbit would have caught the exception?
Merge pull request #418 from alphagov/really_remove_references_to_managed_by_transition

Remove a reference to managed_by_transition from an import rake task
Add a Cancel button to the bulk add preview page

- This uses the OffSiteRedirectChecker and params[:return_path] to
  return the user to where they were before they arrived on the bulk
  add page, so long as it was on the site, otherwise they get returned
  to the site mappings page.
Preserve query parameters for the return_path when adding mappings
Merge pull request #410 from alphagov/bulk_add_preview_cancel_button

Add a Cancel button to the bulk add preview page
Merge pull request #411 from alphagov/change_select_to_radio

Change select boxes to radio buttons for mapping type selection
Split out and label Redirector IPs
Add Fastly Anycast IPs

These are the preferred IP addresses to use for all new root domains (aka
"tlds") which we are redirecting. We will be moving domains pointed at the
Amazon legacy IP as soon as we can.
Merge pull request #420 from alphagov/add_fastly_anycast_ips

Add Fastly anycast IPs
Bump Rails to 4.1.6 for the latest security fixes
Merge pull request #422 from alphagov/bump_rails_to_4.1.6

Bump Rails to 4.1.6 for the latest security fixes