Upgrades and upgrade tests take versions of the form release/stable instead of stable_release:

- Refactor common and gce/upgrade.sh to use arbitrary published releases
- Update hack/get-build to use cluster/common code
- Use hack/get-build.sh in cluster upgrade test logic

docs/admin/cluster-management.md

@@ -74,16 +74,7 @@ The node upgrade process is user-initiated and is described in the [GKE document
 
 Upgrades on open source Google Compute Engine (GCE) clusters are controlled by the `cluster/gce/upgrade.sh` script.
 
-Its usage is as follows:
-
-```console
-cluster/gce/upgrade.sh [-M|-N|-P] -l | <release or continuous integration version> | [latest_stable|latest_release|latest_ci]
-  Upgrades master and nodes by default
-  -M:  Upgrade master only
-  -N:  Upgrade nodes only
-  -P:  Node upgrade prerequisites only (create a new instance template)
-  -l:  Use local(dev) binaries
-```
+Get its usage by running `cluster/gce/upgrade.sh -h`.
 
 For example, to upgrade just your master to a specific version (v1.0.2):
 
@@ -94,7 +85,7 @@ cluster/gce/upgrade.sh -M v1.0.2
 Alternatively, to upgrade your entire cluster to the latest stable release:
 
 ```console
-cluster/gce/upgrade.sh latest_stable
+cluster/gce/upgrade.sh release/stable
 ```
 
 ### Other platforms