specify required false when not stricly required

As some form fields are only required if all the data is submitted for
nested models mark field as not required
Style HTML attachment contacts

- Add some styling to html publication contacts.
- Let the govspeak helper methods accept a heading level for the
  contacts. This was needed due to the auto number level inserter
- Remove texture from heading number backgrounds as it isn't used on the
  main page anymore.
Change logic and false.present? is false
Merge pull request #622 from alphagov/not-all-validations-have-required-fields

specify required false when not stricly required
Merge pull request #623 from alphagov/htmlpub-contacts

Style HTML attachment contacts

https://www.pivotaltracker.com/story/show/52444523