Implement handle_receiving_last_chunk
Implement handle_receiving_last_chunk

Getting to the point where

* handle_accept_chunk
* handle_backpressure_for_chunk
* handle_receiving_last_chunk

need to be more DRY

S24

yangchengjian/riak_cs,yangchengjian/riak_cs,laurenrother/riak_cs,dragonfax/riak_cs,GabrielNicolasAvellaneda/riak_cs,yangchengjian/riak_cs,sdebnath/riak_cs,laurenrother/riak_cs,sdebnath/riak_cs,basho/riak_cs,sdebnath/riak_cs,GabrielNicolasAvellaneda/riak_cs,basho/riak_cs,dragonfax/riak_cs,GabrielNicolasAvellaneda/riak_cs,laurenrother/riak_cs,basho/riak_cs,basho/riak_cs,basho/riak_cs_lfs,dragonfax/riak_cs,yangchengjian/riak_cs,laurenrother/riak_cs,basho/riak_cs_report,dragonfax/riak_cs,sdebnath/riak_cs,GabrielNicolasAvellaneda/riak_cs