Use inline if-else to cleanup HTML

The result from the normal if-else block has linebreak, which result in
poorly formatted HTML code. This should fix it and make the code looks
cleaner.

templates/accordion.html

@@ -7,21 +7,12 @@
 
     <ul>
       % for section in chapter['sections']:
-      <li
-          % if 'active' in section and section['active']:
-            class="active"
-          % endif
-        >
-
+        <li${' class="active"' if 'active' in section and section['active'] else ''}>
           <a href="${reverse('courseware_section', args=format_url_params([course_name, chapter['name'], section['name']]))}">
             <p>${section['name']}</p>
 
             <p class="subtitle">
-              ${section['format']}
-
-              % if 'due' in section and section['due']!="":
-                due ${section['due']}
-              % endif
+              ${section['format']} ${"due " + section['due'] if 'due' in section and section['due'] != '' else ''}
             </p>
           </a>
         % endfor