cmd/getgo: initial commit

Initial commit of getgo, a "one-line installer".

Example use from bash:

  curl -LO https://get.golang.org/$(uname)/go_installer && chmod +x go_installer && ./go_installer && rm go_installer

It's comprised of two parts:

cmd/getgo/server: an App Engine application that redirects users to an
appropriate installer based on the request path, which identifies the
user's operating system. It's deployed to get.golang.org.

cmd/getgo: a cross-compiled binary that does the heavy lifting of
downloading and installing the latest Go version (including setting up
the environment) to the user's system. The installers are served from
the golang GCS bucket.

Currently supported systems:
  linux, darwin, windows / amd64, 386

Authored by Jess Frazelle, Steve Francia, Chris Broadfoot.

Change-Id: I615de86e198d3bd93e418fa23055d00ddbdd99fb
Reviewed-on: https://go-review.googlesource.com/51115
Reviewed-by: Jaana Burcu Dogan <jbd@google.com>
20 files changed