- 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/main/validators.py

@@ -46,7 +46,7 @@ class ValidGovEmail:
         from flask import url_for
         message = '''
             Enter a public sector email address or
-            <a class="govuk-link govuk-link--no-visited-state" href="{}">find out who can use Notify</a>
+            <a class="usa-link" href="{}">find out who can use Notify</a>
         '''.format(url_for('main.features'))
         if not is_gov_user(field.data.lower()):
             raise ValidationError(message)