Allow extract text feature to be controlled by env var
Merge pull request #1269 from alphagov/extract-text-feature-controlled-by-env-var

Allow extract text feature to be controlled by env var
Register more formats with Panopticon

In addition to detailed guides, register consultations, document 
collections, policies, publications, and statistical data sets with 
Panopticon.
Set the correct slug in the RegisterableEdition

Use Whitehall's UrlMaker to build the correct slug for an edition,
including the /government prefix where appropriate.
Changing Panopticon to register all publications

Also removing redunant tests for specific content types
RegisterableEdition has Edition type or subtype

With Model's sometimes having a subtype (eg. Map or Policy Paper), RegisterableEdition.kind will return the Edition's correct type.
Use the global url_maker instead of a new one
Merge pull request #1262 from alphagov/register-moar-formats-with-panopticon

Register moar formats with panopticon