Added the easy to add interfaces and implementations for java.util.concurrent to pave the way for future expansion of avians java.util.concurrent classpath implementation.

classpath/java/util/concurrent/Future.java

@@ -0,0 +1,25 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util.concurrent;
+
+public interface Future<V> {
+  public boolean cancel(boolean mayInterruptIfRunning);
+  
+  public boolean isCancelled();
+  
+  public boolean isDone();
+  
+  public V get() throws InterruptedException, ExecutionException;
+  
+  public V get(long timeout, TimeUnit unit) throws InterruptedException, 
+                                                   ExecutionException, 
+                                                   TimeoutException;
+}