[#59908614] Package for Gor

Building from a branch to include a bugfix. Using the same method as vegeta.
[#59908614] Gor elastigo dependency as patch

Because there doesn't appear to be a better way to include these at the
moment. `go get` doesn't work from Launchpad. We don't have support for
multiple tarballs.
[#59908614] Patch gor version

To indicate that we're building from a branch.
Merge pull request #21 from alphagov/59908614-package_gor

[#59908614] Package Gor