Implement Service interface rather than extending it.

Whether or not a class needs to run as a service is an implementation decision.

briar-api/src/org/briarproject/api/sync/ValidationManager.java

@@ -1,12 +1,10 @@
 package org.briarproject.api.sync;
 
-import org.briarproject.api.lifecycle.Service;
-
 /**
  * Responsible for managing message validators and passing them messages to
  * validate.
  */
-public interface ValidationManager extends Service {
+public interface ValidationManager {
 
 	/** Sets the message validator for the given client. */
 	void setMessageValidator(ClientId c, MessageValidator v);