Update kubernetes to 0.18.0, fix module

pkgs/applications/networking/cluster/kubernetes/default.nix

@@ -2,27 +2,33 @@
 
 stdenv.mkDerivation rec {
   name = "kubernetes-${version}";
-  version = "0.15.0";
+  version = "0.18.0";
 
   src = fetchFromGitHub {
     owner = "GoogleCloudPlatform";
     repo = "kubernetes";
     rev = "v${version}";
-    sha256 = "1jiczhx01i8czm1gzd232z2ds2f1lvs5ifa9zjabhzw5ykfzdjg8";
+    sha256 = "1adbd5n2fs1278f6kz6pd23813w2k4pgcxjl21idflh8jafxsyj7";
   };
 
   buildInputs = [ makeWrapper which go iptables rsync ];
 
   buildPhase = ''
+    GOPATH=$(pwd):$(pwd)/Godeps/_workspace
+    mkdir -p $(pwd)/Godeps/_workspace/src/github.com/GoogleCloudPlatform
+    ln -s $(pwd) $(pwd)/Godeps/_workspace/src/github.com/GoogleCloudPlatform/kubernetes
+
     substituteInPlace "hack/lib/golang.sh" --replace "_cgo" ""
-    GOPATH=$(pwd)
     patchShebangs ./hack
     hack/build-go.sh --use_go_build
+
+    (cd cluster/addons/dns/kube2sky && go build ./kube2sky.go)
   '';
 
   installPhase = ''
     mkdir -p "$out/bin"
     cp _output/local/go/bin/* "$out/bin/"
+    cp cluster/addons/dns/kube2sky/kube2sky "$out/bin/"
   '';
 
   preFixup = ''