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/dashboard/dashboard.html

@@ -19,7 +19,7 @@
 
     {{ ajax_block(partials, updates_url, 'upcoming') }}
 
-    <h2 class="heading-medium">
+    <h2 class="font-body-lg">
       In the last seven days
     </h2>