Display count of resources in the dashboard for an environment

Something we've had trouble with in the past is that since the user doesn't directly write a heat template or nova calls to create VMs, they are surprised when they get billed. A way we could help with that is for the environment page (or a component page) to list resources the user might be paying for (typically block storage and compute instances are the only two).

The topology information already displays this, but short text attached either to each environment in the 'environments' list or when viewing in the 'environment components' page would be useful.

This is dependent on whether it's practical for the API to be able to figure it out for an environment in a reasonably efficient fashion. It probably makes sense to store the information for individual component deployments and sum it later.