- Removed links to the gov uk stylesheets

- Deleted /stylesheets folder
- Removed sass build from gulpfile
- Changed gov links to usa links
- Changed other govuk styles, like breadcrumbs
- Changed name of uk_components file to us_components
- Fixed a few tests that broke on account of the changes

app/templates/content_template.html

@@ -14,7 +14,7 @@
       <div class="tablet:grid-col-2">
         {{ sub_navigation(navigation_links) }}
       </div>
-      <div class="tablet:grid-col-10 padding-left-4 sub-content">
+      <div class="tablet:grid-col-10 padding-left-4 usa-prose site-prose">
     {% else %}
       <div class="tablet:grid-col-10">
     {% endif %}