Fix blog meta category and tag classname (#730)

Use automated and required and recognizable "slug" instead of empty "count".

changes/710.bugfix

@@ -0,0 +1 @@
+Add classname for categories and tags that uses slug, not empty "count".

djangocms_blog/templates/djangocms_blog/includes/blog_meta.html

@@ -21,13 +21,13 @@
     {% if post.categories.exists %}
         {% for category in post.categories.all %}
             {% if category.slug %}
-                <li class="category_{{ forloop.counter }}"><a href="{% url 'djangocms_blog:posts-category' category=category.slug %}" class="blog-categories-{{ category.count }}">{{ category.name }}</a>{% if not forloop.last %}, {% endif %}</li>
+                <li class="category_{{ forloop.counter }}"><a href="{% url 'djangocms_blog:posts-category' category=category.slug %}" class="blog-categories-{{ category.count }} blog-categories-{{ category.slug }}">{{ category.name }}</a>{% if not forloop.last %}, {% endif %}</li>
             {% endif %}
         {% endfor %}
     {% endif %}
     {% if post.tags.exists %}
         {% for tag in post.tags.all %}
-            <li class="tag_{{ forloop.counter }}"><a href="{% url 'djangocms_blog:posts-tagged' tag=tag.slug %}" class="blog-tag blog-tag-{{ tag.count }}">{{ tag.name }}</a>{% if not forloop.last %}, {% endif %}</li>
+            <li class="tag_{{ forloop.counter }}"><a href="{% url 'djangocms_blog:posts-tagged' tag=tag.slug %}" class="blog-tag blog-tag-{{ tag.count }} blog-tag-{{ tag.slug }}">{{ tag.name }}</a>{% if not forloop.last %}, {% endif %}</li>
         {% endfor %}
     {% endif %}
 </ul>