Make skeleton of summary page

This adds some extra elements to the summary page to mockup various
scenarios, primarily:
- What it looks like when you haven't answered a required question
- What actions are available in the footer when you have and haven't
  completed all the required questions for a given lot
Make 'return to submissions a link'

Because it's not an action, because it takes you somewhere
Use new breadcrumb template on new summary page
Rewrite summary page to use real questions

There is still more to do to make this work but this is the first step towards
not having dummy data and buttons in the real app.
[GM] Removed hard-coded summary page data, wired in controller
[GM] changed optional questions
Passed stored values map into summary page to populate data - not fully working
Display assurance answers and service name on summary page
Merge pull request #97 from alphagov/summary-page

Summary page