Introducing top level browsing

We introduce a new /p/<project_url>/browse endpoint, which allows to
see all top-level nodes of a project.

src/templates/projects/browse_embed.pug

@@ -0,0 +1,27 @@
+| {% from '_macros/_asset_list_item.html' import asset_list_item %}
+include ../../../../pillar/src/templates/mixins/components
+| {% block body %}
+#node-container
+	section.d-flex
+		h4.p-4 Browse
+
+	section.node-details-description.px-4.
+		Browse project
+
+	section.container-fluid
+		| {% if nodes %}
+
+		+card-deck(id="asset_list_explore", class="pl-4")
+			| {% for node in nodes %}
+			| {{ asset_list_item(node, current_user) }}
+			| {% endfor %}
+			| {% else %}
+			.list-node-children-container
+				.list-node-children-empty No items... yet!
+		| {% endif %}
+
+	script.
+		// Generate GA pageview
+		ga('send', 'pageview', location.pathname);
+
+| {% endblock %}