Fix bittorrent URL configuration option

This change modifies bittorrent to give URL setting preference to the
configuration option first and then to entry point addins.  The thought
process is that users will want the ability to change the URL
via configuration.  The entry point is code and slower to address.

If the user really wants to use the entry point, they can leave
the configuration option empty.

Existing test cases updated to reflect new priority.

Change-Id: I5af94b4b50531fc7801e70d83b89dd7ed2bcf310
Merge "Fix bittorrent URL configuration option"