Rackspace - Switch to CoreOS for standard cluster

The Rackspace setup for Kubernetes now leverages CoreOS instead of Ubuntu. We've dropped Salt completely for our cluster.
Add Rackspace to build/release.sh

Updates to the build/release.sh scripts to upload build binaries to
Cloud Files.
remove hardcoded cloudfiles path and fix PORTAL_NET
Migrate Rackspace upload scripts to util.sh

The functions to upload built k8s tars to Cloud Files were incorrectly
placed in build/common.sh. These have been migrated to
cluster/rackspace/util.sh
Remove extra newline and update comments in util.sh
bash completions for kubectl

Support pre command flags:
--api-version=
-a, --auth-path=
--certificate-authority=
--client-certificate=
--client-key=
--insecure-skip-tls-verify=
--match-server-version=
-s, --server=

And commands:
get
describe
create
update
delete

Tries to be smart about things like

kubectl get -o template  requires a template file

It also tries to accept both sigular and plural versions of all
resources.  Even though it will only complete to the plural version.
Replace custom proxy with httputil.ReverseProxy for kubecfg/kubectl.

Fixes #1149 - kubecfg proxy "411 Length Required" error on POST/PUT.
build: switch to golang:1.3 and build go for KUBE_CROSSPLATFORMS
build: add kube-build:cross base
build: fix golang pull message
Update k8s201.md

Minor typo corrected.
Merge pull request #1943 from oaktowner/patch-1

Update k8s201.md
Update gce.md

Fixed a minor typo (and capitalized Kubernetes, which seems to be consistent with usage elsewhere).
Podex handling multiple images
Merge pull request #1947 from oaktowner/patch-2

Update gce.md
Merge pull request #1898 from jhadvig/podex_images

Podex handling multiple images
Add create/delete minion to client interface.
Script to do an "official" release push to GCS.
Fix GCE since KUBE_ADMIN_TOKEN is never set, since get-admin-token is never called.
Merge pull request #1952 from brendandburns/fix

Fix GCE since KUBE_ADMIN_TOKEN is never set,