Fix for parse error of HTTP response that has additional chunks after
the first zero length chunk.  Previously there would be no error
thrown, if it was just an additional HTTP reply directly after, but
if there is a chunk length rather then a 'H' character a parse error would
be raised.

This patch just discards the rest of the data after the terminating zero
length chunk and possibly trailing headers.

This bug was noticed when crawling amazon.com as part of bug.

https://github.com/joyent/node/issues/5479