Added isUpdateInProgress() to UpdaterManager interface.

core/java/src/net/i2p/update/UpdateManager.java

@@ -145,6 +145,12 @@ public interface UpdateManager {
      */
     public String checkAvailable(UpdateType type, String id, long maxWait);
     
+    /**
+     *  Is any download in progress?
+     *  Does not include checks.
+     */
+    public boolean isUpdateInProgress();
+    
     /**
      *  Non-blocking. Does not check.
      *  Fails if check or update already in progress.