Updating site to use USWDS styles (#509)

* Updated header and footer
* Updated fonts
* Moved files around and updated gulpfile to correct the build process when it goes to production
* Adjusted grid templating
* Added images to assets
* Update app/templates/components/uk_components/footer/template.njk

Co-authored-by: Steven Reilly <stvnrlly@users.noreply.github.com>

app/templates/views/pricing/billing-details-signed-out.html

@@ -9,7 +9,7 @@
 
     {{ page_header('Billing details') }}
 
-    <p class="govuk-body">
+    <p>
       <a class="govuk-link" href="{{ url_for('.sign_in', next=url_for('.billing_details')) }}">Sign in</a> to see our:
     </p>
 
@@ -19,7 +19,7 @@
       <li>invoice address</li>
     </ul>
 
-    <p class="govuk-body">
+    <p>
       You can use this information to add the Cabinet Office as a supplier. Your organization may need to do this before you can raise a purchase order.
     </p>