Remove <h2> tag around service name in nav

The heading structure of most pages is incorrect (`<h2>` followed by
`<h1>`). The `<h1>` indicates the main purpose of the page, the service
name (currently the first `<h2>`) doesn't need to be a heading.

app/assets/stylesheets/components/navigation.scss

@@ -9,7 +9,7 @@
     margin: 0 0 10px;
     position: relative;
 
-    h2 {
+    &-name {
       @include bold-19;
       margin: 0 0 0 0;
     }

app/templates/withnav_template.html

@@ -7,9 +7,9 @@
 {% block fullwidth_content %}
   <div id="content">
     <div class="navigation-service">
-      <h2 class="navigation-service-name">
+      <div class="navigation-service-name">
         {{ current_service.name }}
-      </h2>
+      </div>
       <a href="{{ url_for('main.choose_service') }}" class="navigation-service-switch">Switch service</a>
     </div>
     <div class="grid-row">

tests/app/main/views/test_dashboard.py

@@ -105,7 +105,6 @@ def test_should_show_recent_templates_on_dashboard(
 
     page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
     headers = [header.text.strip() for header in page.find_all('h2') + page.find_all('h1')]
-    assert 'Test Service' in headers
     assert 'In the last 7 days' in headers
 
     table_rows = page.find_all('tbody')[1].find_all('tr')

tests/app/main/views/test_service_settings.py

@@ -102,7 +102,7 @@ def test_show_restricted_service(
     response = logged_in_client.get(url_for('main.service_settings', service_id=service_one['id']))
     page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
     assert page.find('h1').text == 'Settings'
-    assert page.find_all('h2')[1].text == 'Your service is in trial mode'
+    assert page.find_all('h2')[0].text == 'Your service is in trial mode'
 
 
 def test_switch_service_to_live(