Address system dependence of sed in tests (#339)
Address system dependence of sed in tests (#339)

`sed` was being used in the `http-e2e.js` test with the `-i` flag
to perform changes in-place.  However, this option has a different
syntax on OS X vs Linux.  As a fix, `-i.bak` is now used to
explicitly specify a backup extension works on both OS X and
Linux.

PR-URL: https://github.com/GoogleCloudPlatform/cloud-trace-nodejs/pull/339
googleapis/cloud-trace-nodejs,keymetrics/trassingue,keymetrics/vxx,matthewloring/cloud-trace-nodejs,keymetrics/trassingue,googleapis/cloud-trace-nodejs,keymetrics/vxx,googleapis/cloud-trace-nodejs,matthewloring/cloud-trace-nodejs,googleapis/cloud-trace-nodejs,matthewloring/cloud-trace-nodejs