= can: fix PipelineLimiter which only worked for chunked requests, fix #414

Some things to keep in mind:
  * It may take quite a while until Tcp.SuspendReading gets to the networking part. In
    this time quite a bit of data may already be in queues to be processed.
  * PipelineLimiting doesn't work at all with fast-path because all the request processing is done instantly,
    i.e. during the `eventPL` call in handleEvent the complete request is handled and already sent
    out so that the openRequests counter is never increased.
Merge pull request #457 from jrudolph/i/414/fix-pipeline-limiter

= can: fix PipelineLimiter which only worked for chunked requests, fix #414