provide app lookup error reasons (bug 870020)

Author: spasovski

hearth/templates/detail/main.html

@@ -23,7 +23,19 @@ <h3>{{ _('Loading...') }}</h3>
   {% except %}
     <div class="detailed-error">
       <h2>{{ _('Oh no!') }}</h2>
-      <p>{{ _('The page you were looking for was not found.') }}</p>
+      {% if error == 403 %}
+        <p>{{ _('The app requested is not public.') }}</p>
+      {% elif error == 404 %}
+        <p>{{ _('The app requested was not found.') }}</p>
+      {% elif error == 451 %}
+        <p>{{ _('The app requested is not available for your region.') }}</p>
+      {% elif error == 500 %}
+        <p>{{ _('A server error occurred.') }}</p>
+      {% endif %}
+
+      {% if not error %}
+        <p>{{ _('A connection error occurred.') }}</p>
+      {% endif %}
     </div>
   {% end %}
 </section>