prevent timeouts from causing forever empty TMVars for pipelining
Merge pull request #21 from edahlgren/pipelining-craziness

prevent timeouts from causing forever empty TMVars for pipelining
up the version
do not count pipelined requests in concurrency because they don't touch riak
handle errors at the highest point
Merge pull request #22 from edahlgren/pipeline-nolimit

concurrency limits shouldn't involve pipelined requests