releasehelper: fix test to be OS-agnostic (#2268)
releasehelper: fix test to be OS-agnostic (#2268)

* Fix releasehelper test to be OS-agnostic w.r.t. path separators

Fixes #2264

* Temporarily rig travis file to run test on Windows

* Remove Windows hack - tests pass

google/go-cloud,google/go-cloud,google/go-cloud