put gh.rb in the right place

Merge pull request cli#298 from cli/scoop

scoop config for gh

ok right duh

try and change bucket name

s/-/_/

add scoop config to goreleaser

Merge pull request cli#272 from cli/windows-urls

Fix `pr create` preview in browser flow for Windows

Consistently use `checkout@v2`

Absolute paths to go-msi

Simplify downloading of `gh.exe`

Now that there is a ZIP archive to download, to avoid the complexities
of unzipping through Node.js we use `hub release download && unzip` via bash.