Include unique device ID in transport updates.

briar-api/src/org/briarproject/api/DeviceId.java

@@ -0,0 +1,16 @@
+package org.briarproject.api;
+
+import java.util.Arrays;
+
+/** Type-safe wrapper for a byte array that uniquely identifies a device. */
+public class DeviceId extends UniqueId {
+
+	public DeviceId(byte[] id) {
+		super(id);
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof DeviceId && Arrays.equals(id, ((DeviceId) o).id);
+	}
+}