dashboard: add open graph tags

circle/dashboard/templates/base.html

@@ -8,6 +8,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <meta name="description" content="">
     <meta name="author" content="">
+    {% include "open-graph.html" %}
     <link rel="icon" type="image/png" href="{% static "dashboard/img/favicon.png" %}"/>
 
     <title>{% block title %}{% block title-page %}{% endblock %} | {% block title-site %}CIRCLE{% endblock %}{% endblock %}</title>

circle/dashboard/templates/open-graph.html

+{# use absolute url in production #}
+<meta property="og:image" content="/static/dashboard/img/og-logo.png"/>
+<meta property="og:site_name" content="CIRCLE Cloud - devenv"/>
+<meta property="og:title" content="CIRCLE Cloud - devenv"/>
+<meta property="og:type" content="website"/>