Store and exchange client minor versions.

These don't affect client visibility.

bramble-api/src/main/java/org/briarproject/bramble/api/properties/TransportPropertyManager.java

@@ -22,6 +22,11 @@ public interface TransportPropertyManager {
 	 */
 	int MAJOR_VERSION = 0;
 
+	/**
+	 * The current minor version of the transport property client.
+	 */
+	int MINOR_VERSION = 0;
+
 	/**
 	 * Stores the given properties received while adding a contact - they will
 	 * be superseded by any properties synced from the contact.

bramble-api/src/main/java/org/briarproject/bramble/api/sync/ClientVersioningManager.java

@@ -25,7 +25,7 @@ public interface ClientVersioningManager {
 	 * Registers a client that will be advertised to contacts. This method
 	 * should be called before {@link LifecycleManager#startServices(String)}.
 	 */
-	void registerClient(ClientId clientId, int majorVersion);
+	void registerClient(ClientId clientId, int majorVersion, int minorVersion);
 
 	/**
 	 * Registers a hook that will be called when the visibility of the given