Refactored method to use duplicate in speech_type
Added Bylined Article as a speech type

After discussion with @heathd we decided that this isn't a brilliant
abstraction, but it doesn't make the current stretching of the
definition of "speech" any worse than it already is, so we're going to
stick with it for now.

The "right" solution is to create a new edition type, but that's a very
heavyweight operation currently.
Correct indentation
Implement authored articles as speech type
Adding translations
Fix hash syntax
Add translation removed by rake task
Publish location relevancy to Javascript
Pull speech type data structure to helper method
Encode speech type structure in JS file directly

We only want the English version to be used in admin, so having the
data structure use the default locale and set it globally is perfectly
acceptable. This removes the need for the embedded <script> tag in the
form partial. Note that some calls to the translation helper method
`t` have had to be updated to go through the I18n module, as helpers
have to be explicitly included when evaluating the asset Erb template.
Merge pull request #439 from alphagov/authored-articles

Tracker: https://www.pivotaltracker.com/story/show/46394133

Allow authored (or 'bylined') articles