[Federation][join-01] Implement `kubefed join` command.

federation/pkg/kubefed/BUILD

+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_binary",
+    "go_library",
+    "go_test",
+    "cgo_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["join.go"],
+    tags = ["automanaged"],
+    deps = [
+        "//pkg/api:go_default_library",
+        "//pkg/client/unversioned/clientcmd:go_default_library",
+        "//pkg/client/unversioned/clientcmd/api:go_default_library",
+        "//pkg/kubectl:go_default_library",
+        "//pkg/kubectl/cmd:go_default_library",
+        "//pkg/kubectl/cmd/templates:go_default_library",
+        "//pkg/kubectl/cmd/util:go_default_library",
+        "//pkg/runtime:go_default_library",
+        "//vendor:github.com/golang/glog",
+        "//vendor:github.com/spf13/cobra",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["join_test.go"],
+    library = "go_default_library",
+    tags = ["automanaged"],
+    deps = [
+        "//federation/apis/federation/v1beta1:go_default_library",
+        "//pkg/api:go_default_library",
+        "//pkg/api/testapi:go_default_library",
+        "//pkg/api/unversioned:go_default_library",
+        "//pkg/api/v1:go_default_library",
+        "//pkg/apimachinery/registered:go_default_library",
+        "//pkg/client/restclient:go_default_library",
+        "//pkg/client/restclient/fake:go_default_library",
+        "//pkg/client/typed/dynamic:go_default_library",
+        "//pkg/client/unversioned/clientcmd:go_default_library",
+        "//pkg/client/unversioned/clientcmd/api:go_default_library",
+        "//pkg/kubectl/cmd/testing:go_default_library",
+        "//pkg/kubectl/cmd/util:go_default_library",
+        "//pkg/runtime:go_default_library",
+    ],
+)

hack/verify-flags/known-flags.txt

@@ -242,6 +242,7 @@ host-ipc-sources
 host-network-sources
 host-pid-sources
 host-port-endpoints
+host-system-namespace
 hostname-override
 http-check-frequency
 http-port

test/test_owners.csv

@@ -480,6 +480,7 @@ k8s.io/kubernetes/federation/pkg/federation-controller/util,bgrant0607,1
 k8s.io/kubernetes/federation/pkg/federation-controller/util/eventsink,luxas,1
 k8s.io/kubernetes/federation/pkg/federation-controller/util/planner,Q-Lee,1
 k8s.io/kubernetes/federation/pkg/federation-controller/util/podanalyzer,caesarxuchao,1
+k8s.io/kubernetes/federation/pkg/kubefed,madhusudancs,0
 k8s.io/kubernetes/federation/registry/cluster,nikhiljindal,0
 k8s.io/kubernetes/federation/registry/cluster/etcd,nikhiljindal,0
 k8s.io/kubernetes/hack/cmd/teststale,thockin,1