Http::request - get callers for ApiService::foreignCall and report to Logstash

@wladekb / @jcellary 

``ApiService:: foreignCall`` is being reported to Logstash. Adding it to the "blacklist" of ``wfGetCallerClassMethod`` function will report the "real" caller and make stats more meaningful.

```json
{
  "stats": {
   "count": 6400, 
   "max": 7542.0, 
   "sum": 692130.0, 
   "avg": 108.1453125, 
   "min": 10.0
  }, 
  "key": "apiservice:foreigncall"
 }
```