Move memory to gossip since that's what it is

options.go

@@ -0,0 +1,15 @@
+package gossip
+
+import (
+	"github.com/micro/go-micro/registry"
+
+	"golang.org/x/net/context"
+)
+
+type contextSecretKey struct{}
+
+func SecretKey(k []byte) registry.Option {
+	return func(o *registry.Options) {
+		o.Context = context.WithValue(o.Context, contextSecretKey{}, k)
+	}
+}