mod_http_oauth2: Improve error messages for URI properties Since there are separate validation checks for URI properties, including that they should use https, with better and more specific error reporting. Reverts 'luaPattern' to 'pattern' which is not currently supported by util.jsonschema, but allows anything that retrieves the schema over http to validate against it, should they wish to do so.

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"
      }
   }
}
```