Display timestamps on the first page of a travel advice edition.
Add updated_at to the stub artefact in TravelAdviceControllerTest
Ensure the edition parameter is passed into the part paths
Tidy up integration test
Build an initial part if no parts are present

For travel advice, the content API will return a
successful response with country details regardless
of whether a published TravelAdviceEdition exists
or not.

In this commit, we catch when this is the case
(where @publication.parts is not present) and build
a stub "summary" part so that we can still display
a skeleton travel advice page for the country.
Show a link to a printer-friendly page

This isn't built yet - the link will just redirect
back to the root page of the travel advice.
Set the locale for a travel advice artefact.
Split apart guide navigation templates

Despite the additional logic added to the guide
navigation templates, there is now a need to add 
further changes to the travel advice guide navigation.

In light of this, I'm splitting the templates apart
into separate guide/benefit and travel-advice partials 
so we can keep them as simple as possible.
Add "current travel advice" description to Summary part

This is dependent on styles added to static
Merge remote branch 'origin/travel-advice-amends'