Refactored kube-push.sh script

The script allows also to push binaries only to the master or specified node.
Added support for released tars.

Introduced new push methods and implemented them for GCE.

cluster/kube-util.sh

@@ -47,11 +47,26 @@ function kube-down {
 	echo "TODO"
 }
 
-# Update a kubernetes cluster with latest source
+# Update a kubernetes cluster
 function kube-push {
 	echo "TODO"
 }
 
+# Prepare update a kubernetes component
+function prepare-push {
+	echo "TODO"
+}
+
+# Update a kubernetes master
+function push-master {
+	echo "TODO"
+}
+
+# Update a kubernetes node
+function push-node {
+	echo "TODO"
+}
+
 # Execute prior to running tests to build a release if required for env
 function test-build-release {
 	echo "TODO"