Also includes other improvements:
- Makefile rule to run tests against remote instance using existing host or image
- Makefile will reuse an instance created from an image if it was not torn down
- Runner starts gce instances in parallel with building source
- Runner uses instance ip instead of hostname so that it doesn't need to resolve
- Runner supports cleaning up files and processes on an instance without stopping / deleting it
- Runner runs tests using `ginkgo` binary to support running tests in parallel
- Add README.md for node e2e tests
- Add support for --cleanup=false to leave test files on remote hosts and temporary instances for debugging
- Add ubuntu trusty instances for docker 1.8 and docker 1.9 to jenkins pr builder
- Disable coreos-beta for jenkins ci since it is failing - need to investigate
