Static links to latest binaries

[zack-shoylev]

Please make static links available for the latest binaries, instead of the current links (current links are in this form: https://ec4a542dbf90c03b9f75-b342aba65414ad802720b41e8159cf45.ssl.cf5.rackcdn.com/1.1.0-beta1/Linux/amd64/rack)

This is needed to make it easier to develop and update docker images, for example.

[carolynvs]

While we may not want to just use the existing infrastructure of download.getcarina.com that we are using to provide this exact feature for carina and dvm (since rack isn't really for Carina), maybe we can rip off their cloud files deploy script.

[etoews]

Conceivably, if we had something like https://download.developer.rackspace.com/latest/Linux/amd64/rack we wouldn't have to worry about updating images at all. We could create an automated build for rack at https://hub.docker.com/u/rackspace/rack/ and the rackspace/rack:latest would always truly be the latest based on the master branch.

If users wanted specific point in time versions like rackspace/rack:1.2.0, we could do that but I'm not even sure that's necessary for a CLI like this.