Improve web view of repos

This patch adds total count of repos, displays their primary ids
(useful for API manipulation).

It also enables sorting and filtering of the table.

JIRA: PDC-978

pdc/apps/release/templates/release_detail.html

@@ -74,9 +74,10 @@ <h3 class="sub-header">{% trans 'Variants' %}</h3>
 </table>
 
 <h3 class="sub-header">{% trans 'Repositories' %}</h3>
-<table class="table table-striped">
+<table class="datatable table table-striped table-bordered" data-paging="false">
  <thead>
   <tr>
+    <th class="text-right">#</th>
     <th>{% trans "Variant.Arch" %}</th>
     <th>{% trans "Service" %}</th>
     <th>{% trans "Repo Family" %}</th>
@@ -92,6 +93,7 @@ <h3 class="sub-header">{% trans 'Repositories' %}</h3>
 {% for variantarch in variant.variantarch_set.all %}
 {% for repo in variantarch.repos.all %}
   <tr>
+    <td class="text-right">{{ repo.pk }}</td>
     <td>{{ variant.variant_uid }}.{{ variantarch.arch }}</td>
     <td>{{ repo.service }}</td>
     <td>{{ repo.repo_family }}</td>