Adding missing final statements

When compiled with Java8 there were no errors but when compiled
with Java7 there were compile errors about missing final statements
for variable use inside an inner-class.

Author: vaage

src/codeu/chat/server/Server.java

@@ -56,7 +56,7 @@ public final class Server {
   private final Relay relay;
   private Uuid lastSeen = Uuids.NULL;
 
-  public Server(Uuid id, byte[] secret, Relay relay) {
+  public Server(final Uuid id, final byte[] secret, final Relay relay) {
 
     this.id = id;
     this.secret = Arrays.copyOf(secret, secret.length);