Add vendoring

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

vendor/github.com/docker/engine-api/client/plugin_remove.go

@@ -0,0 +1,14 @@
+// +build experimental
+
+package client
+
+import (
+	"golang.org/x/net/context"
+)
+
+// PluginRemove removes a plugin
+func (cli *Client) PluginRemove(ctx context.Context, name string) error {
+	resp, err := cli.delete(ctx, "/plugins/"+name, nil, nil)
+	ensureReaderClosed(resp)
+	return err
+}