Use cross-platform /dev/null file

Issue raised in this Stack Overflow question:
http://stackoverflow.com/questions/17602148/how-to-deploy-cloudfoundry-to-aws

Answer from here:
http://stackoverflow.com/a/8682009/126042
add rspec as development dependency
Add missing module declaration
convert to single quotes
add `--verbose` flag to `s3cmd sync`
Avoid needless chdir; reduce knowledge of WORKSPACE
[director] Fix a race condition when changing network spec [fixes #53738423]
Conceal knowledge about stemcells in pipeline
Inline knowledge of latest to make it easier to switch to build number
Infrastructure knows valid names
Conceal stemcell names in pipeline
rename for clarity
[Finishes #52671359] Use current build to refer to stemcells in pipeline
Use polymorphism instead of primitives and conditionals
Spec each infrastrcuture directly for clarity
Introduce hypervisor notion so we can use it in the stemcell filename
Inject infratrcuture object instead of primitive name
[#53976067] bosh-dev knows that openstack stemcell name includes hypervisor
ci_build.sh display sorted `env`

 * moving this out of jenkins
Add meta task to encapsulate ci:setup:rspec + unit/integration

  * move logic out of Jenkins
  * fix .gitignore for JUnit reports