mod_http_admin_api: Tweak token session to please module:may() module:may() checks for type == "c2s", but mod_tokenauth does not currently include that or most common session properties. Fixes a traceback resulting from a different code path where module:may() tries to index event.stanza, which does not exist for http events.

Prosody 0.12 added an API allowing modules to report their status. This
module allows reading these statuses via HTTP for use in monitoring.

```
$ curl http://prosody.localhost:5280/status
{
   "example.com" : {
      "c2s" : {
         "message" : "Loaded",
         "type" : "core"
      }
   }
}
```