tagging fix for yaml

Author: Gergo Rozsa

templates/agent-conf.d/cassandra.yaml.erb

@@ -11,7 +11,7 @@ instances:
 <% if @tags.length > 0 -%>
     tags:
 <%- @tags.each do |tag_name, tag_value| -%>
-      <%= tag_name %>: <%= tag_value %>
+      - <%= tag_name %>:<%= tag_value %>
 <% end -%>
 <% end -%>