Update download URI

[sgerrand]

💁 The download URIs for Go have changed. This changeset updates the base URL and removes the unrequired version branching.

Closes #12

[sgerrand]

👋 @wfarr: For your consideration.

[spraints]

This doesn't work for me.

$ bin/goenv install 1.6.2

curl: (22) The requested URL returned error: 404 Not Found
goenv: unable to install Go `1.6.2' from binary, download not available at https://storage.googleapis.com/golang/go1.6.2.darwin-amd64-osx10.8.tar.gz

[sgerrand]

@spraints: Looks like the packages have changed markedly since "install" was implemented. https://storage.googleapis.com/golang/go1.6.2.darwin-amd64-osx10.8.tar.gz should be https://storage.googleapis.com/golang/go1.6.2.darwin-amd64.pkg or https://storage.googleapis.com/golang/go1.6.2.darwin-amd64.tar.gz

[sgerrand]

Looking at the Go downloads page, the format change in OS X package naming happened between version 1.4.2 and 1.4.3.

[sgerrand]

👋 @spraints: goenv install 1.6.2 should work for you as of 640b2a7. ♻️

[spraints]

Looks great! Thanks!