Ability to add a default mapping for subversion author to username

Currently you need to add a mapping for each repository, however in most cases the author name in svn does not change across multiple repositories, so it would be good to add a default mapping from your fisheye username to repository author name.

While we are at it we should allow multiple default mappings, e.g. parthak, partha, should be mapped to my fisheye username pkamal. If either of these usernames appear in any of the repositories, they should be mapped to me.

Kind Regards,
Partha Kamal