Use binary releases for cluster push scripts.

This is for GCE right now.  Other clouds/clusters are probably broken.
Tweak salt docs a little
Vagrant now using pre-built binaries.
Fix up kubecfg.sh script to find correct binary.
Remove unused manifest file
GCS uploads as part of release are now marked public and non-cached by default.
Normalize some of the boilerplate in each of the `build` commands.
Update build/README.md
Clean up READMEs and broken stuff.

Move all support for clouds that are broken with this change into an `icebox` directory.  We'll move that stuff back out as we fix it up.
Standardize how we refer to the kubernetes root.

Now use $KUBE_ROOT as the variable pretty much everywhere.
Set shell options for reliability.

Tweak a few other small things in our shell scripts.
Confirm pull of golang:cross as it is huge (1.8G)
Option in `build/release.sh` to skip tests for a quicker dev/test cycle.
Add a `release` target to `Makefile`

The rest of the reconciliation with new `build` methods will come later.
Apply SELinux policy to _output dir so "build in docker" works on RHEL.
Uniquify docker names

If you have two repos that are both building at the same time we don't want to have them stomp on each other as they deal with docker.  Work around this by hashing the KUBE_ROOT and mixing that in to the name.
Merge pull request #1532 from jbeda/binary-deploy

Binary deploy