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>

tests/app/main/views/service_settings/test_service_settings.py

@@ -252,7 +252,7 @@ def test_should_show_service_name(
     assert page.find('h1').text == 'Change your service name'
     assert page.find('input', attrs={"type": "text"})['value'] == 'service one'
     assert page.select_one(
-        'main p'
+        'main .govuk-body'
     ).text == 'Your service name should tell users what the message is about as well as who it’s from.'
     assert normalize_spaces(page.select_one('main ul').text) == (
         'at the start of every text message '
@@ -310,7 +310,7 @@ def test_should_show_service_name_with_no_prefixing(
     page = client_request.get('main.service_name_change', service_id=SERVICE_ONE_ID)
     assert page.find('h1').text == 'Change your service name'
     assert page.select_one(
-        'main p'
+        'main .govuk-body'
     ).text == 'Your service name should tell users what the message is about as well as who it’s from.'