Path is baked in. Entry is private. Dispatcher can change.

```
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] 
[INFO] Flow (Parent) ...................................... SUCCESS [  0.276 s]
[INFO] Flow ............................................... SUCCESS [  3.890 s]
[INFO] Flow Sample ........................................ SUCCESS [  9.570 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 14.663 s
[INFO] Finished at: 2014-11-08T18:41:12-08:00
[INFO] Final Memory: 64M/719M
[INFO] ------------------------------------------------------------------------
```
This all kind of goes without saying, I think.  If not it could be a little clearer:  "Set a dispatcher which will be called for all future Traversals. If a Traversal is currently in progress with a previous Dispatcher, that Traversal will not be affected."