Bump Slimmer to get the new core_layout
Use new core_layout
Remove govspeak scss

We don't need this anymore as it's coming from the components.
Use components and grid layout for content

This commit uses the new govspeak component and grid layout for it and
the sidebar. It also removes the call for the govspeak SCSS and the
sidebar positioning SCSS that is now provided for the grid layout.
Use title and metadata component

Using this also requires changing the helpers to return the hashes in a
slightly different format. This commit also removes the SCSS that was
style these parts of the page.
Remove unnecessary SCSS

With the new grid layout, we had a bunch of SCSS style the page that we
don't need anymore. This commit remvoes that.
Expose extra_date_metadata as a public method

In order to pass the dates correctly to the components, the extra dates
need passed in by themselves. This commit exposes the dates as public
methods.
Use new layout for summary
Use document footer component and show history

In order to show the change history we wanted to use the new document
footer component. This commit removes the SCSS for the footer and pass
the required locals through to the footer.
Update steps to use components

With using the new component library, we can't return the component HTML
in tests. Instead we return a JSON blob. This commit updates the tests
to look for the text inside the JSON.
Bump Slimmer to 5.1

Bump Slimmer to 5.1 to get the new components test version which allows
the tests to pass.

Also let Cabybara see hidden elements so it can see the script tag with
the JSON inside it.
Merge pull request #64 from alphagov/change-notes-and-components

Change notes and components