Fix some issues with initialisation

selector/selector.go

@@ -64,6 +64,8 @@ import (
 // and mark their status. This allows host pools and other things
 // to be built using various algorithms.
 type Selector interface {
+	Init(opts ...Option) error
+	Options() Options
 	// Select returns a function which should return the next node
 	Select(service string, opts ...SelectOption) (Next, error)
 	// Mark sets the success/error against a node