Add support for usage stats?

[uniqueg]

Certainly nothing urgent and not something we have a very concrete use case for at ELIXIR, but it may still be nice for admins/orgs to be able to tell how often a service was used. Of course it's debatable whether this info should be available publicly and for every service, but I thought I'd just put the idea out anyways.

Some possible stats:

• Status code of last request
• Time of last request
• Uptime
• Total number of requests
  etc