Fix not-an-actual-bug of multipart upload listing
Fix not-an-actual-bug of multipart upload listing

2i for listing MP uploads should use equal query but the function
riakc_pb_socket:get_range/5 was used which is for range query.  But,
so luckily, this bug did not manifests for user facing response.

The reason was two-fold,
1. only 2i key is important and value is always <<"1">> for MP 2i, and
2. Timeout value 60000 (integer) is larger than <<"1">> after
   converted to binary.

So this commit fixes a bug that has not became reality ever.

dragonfax/riak_cs,GabrielNicolasAvellaneda/riak_cs,basho/riak_cs,dragonfax/riak_cs,yangchengjian/riak_cs,yangchengjian/riak_cs,basho/riak_cs,GabrielNicolasAvellaneda/riak_cs,dragonfax/riak_cs,GabrielNicolasAvellaneda/riak_cs,dragonfax/riak_cs,basho/riak_cs,yangchengjian/riak_cs,yangchengjian/riak_cs,GabrielNicolasAvellaneda/riak_cs,basho/riak_cs