Fix accumulator test random failure
Fix accumulator test random failure

The failure was caused by calls to the postspy being
batched together despite the fact that the postspy logic
expected each usage record to come individually. The postspy
logic now properly maps over each request in the batch instead
of just using the first request.

Fixes #155

sasrin/cf-abacus,nmaslarski/cf-abacus,pombredanne/cf-abacus,danparsons/cf-abacus,jsdelfino/d-abacus,danparsons/cf-abacus,cloudfoundry-incubator/cf-abacus,rajkiranrbala/cf-abacus,jsdelfino/d-abacus,rajkiranrbala/cf-abacus,jsdelfino/cf-abacus-experiment,jsdelfino/x-abacus,18F/cf-abacus,cloudfoundry-incubator/cf-abacus,jsdelfino/x-abacus,KRuelY/cf-abacus,rajkiranrbala/cf-abacus,18F/cf-abacus,KRuelY/cf-abacus,KRuelY/cf-abacus,jsdelfino/x-abacus,KRuelY/cf-abacus,BetaFood/cf-abacus-dev,cloudfoundry-incubator/cf-abacus,danparsons/cf-abacus,jsdelfino/d-abacus,jsdelfino/x-abacus,BetaFood/cf-abacus-dev,sasrin/cf-abacus,rajkiranrbala/cf-abacus,pombredanne/cf-abacus,jsdelfino/cf-abacus-experiment,jsdelfino/d-abacus,nmaslarski/cf-abacus,pombredanne/cf-abacus,jsdelfino/cf-abacus-experiment,pombredanne/cf-abacus,18F/cf-abacus,nmaslarski/cf-abacus,nmaslarski/cf-abacus,sasrin/cf-abacus,BetaFood/cf-abacus-dev