Make go version requirements clearer

hack/lib/golang.sh

@@ -240,12 +240,12 @@ EOF
   if [[ "${TRAVIS:-}" != "true" ]]; then
     local go_version
     go_version=($(go version))
-    if [[ "${go_version[2]}" < "go1.2" ]]; then
+    if [[ "${go_version[2]}" < "go1.4" ]]; then
       kube::log::usage_from_stdin <<EOF
 
 Detected go version: ${go_version[*]}.
-Kubernetes requires go version 1.2 or greater.
-Please install Go version 1.2 or later.
+Kubernetes requires go version 1.4 or greater.
+Please install Go version 1.4 or later.
 
 EOF
       exit 2