BodyReader API issue.. [Attention ICAP folk]

Working on bug 772, I've tracked it down thusly:

When we call initiateClose, we dont fully free the BodyReader, because
the one on conn is preserved. If we dont fully free it, then we dont
discard the body, it just spools forever because theres no callback.

If we do free the bodyreader, we trigger an assert because the abort
function expects to be called only once.

I dont see any unit tests for icap's dependence on the API, so I haven't
changed BodyReader to address this, what I am doing is poking into it
from ConnStateData - calling consume on the aborted bytes - as that
seemed the easiest fix to me.

I think a better api for the BodyReader would be an explicit 'abort()'
call, which once called would continue to read, discarding the data
without needing a callback.

-Rob

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