Require code generators

* I had to change the constraint for repo-infra from a pinned revision
to master. I was running into dependency hell otherwise. Can revisit if
necessary

Gopkg.toml

@@ -1,3 +1,18 @@
+# Force dep to vendor the code generators, which aren't imported just used at dev time.
+# Picking a subpackage with Go code won't be necessary once https://github.com/golang/dep/issues/1306 is implemented.
+required = [
+  "github.com/jteeuwen/go-bindata/go-bindata",
+  "k8s.io/code-generator/cmd/defaulter-gen",
+  "k8s.io/code-generator/cmd/deepcopy-gen",
+  "k8s.io/code-generator/cmd/conversion-gen",
+  "k8s.io/code-generator/cmd/client-gen",
+  "k8s.io/code-generator/cmd/lister-gen",
+  "k8s.io/code-generator/cmd/informer-gen",
+  "k8s.io/code-generator/cmd/openapi-gen",
+  "k8s.io/gengo/args",
+  "github.com/kubernetes/repo-infra/kazel",
+]
+
 [[constraint]]
   name = "github.com/coreos/etcd"
   version = "3.2.9"
@@ -21,6 +36,10 @@
 # We want Nov 4, 2014 version as the Jul 24, 2015 version (latest version)
 # introduces bug documented in issue 1187
 [[constraint]]
+  name = "github.com/golang/glog"
+  branch = "master" # The master branch constraint allows dep to solve because other dependencies use master.
+
+[[override]] # The override tells dep to use a specific revision when populating _our_ vendor directory. It doesn't help consumers.
   name = "github.com/golang/glog"
   revision = "44145f04b68cf362d9c4df2182967c2275eaefed"
 
@@ -29,3 +48,23 @@
 [[constraint]]
   name = "k8s.io/kube-openapi"
   revision = "868f2f29720b192240e18284659231b440f9cda5"
+
+# Code generators and dev tools
+[[constraint]]
+  name = "github.com/jteeuwen/go-bindata"
+  branch = "master"
+
+[[constraint]]
+  name = "k8s.io/code-generator"
+  version = "kubernetes-1.8.0"
+
+# Keep exactly in sync with github.com/kubernetes/code-generator deps
+# See https://github.com/kubernetes/code-generator/blob/release-1.8/Godeps/Godeps.json
+# This won't be necessary once https://github.com/golang/dep/issues/1335 is implemented or k8s switches to dep.
+[[constraint]]
+  name = "k8s.io/gengo"
+  revision = "9e661e9308f078838e266cca1c673922088c0ea4"
+
+[[constraint]]
+  name = "github.com/kubernetes/repo-infra"
+  branch = "master"