Support multiple processors with the same name

This is mostly for necessary for the outgoing

  * Substation::Processor::Wrapper
  * Substation::Processor::Transformer

processors which are typically registered using
:wrap and :transform as their names. It's fine to
call them multiple times in a row and since they
are outgoing processors, they have no failure
chain attached anyway. Therefore, redefining the
failure chain wouldn't be possible thus removing
the need to access them by name.

Maybe I can come up with a cleaner separation of
concerns in the future.

All integration specs pass now!