ENH: remove .bak files

Came from

$> git log **/*.bak
commit 310d6daba8e6dcc448271eb1b2b35a0876cfa934
Author: Sol Simpson <sds-git@isolver-software.com>
Date:   Tue May 7 06:24:52 2013 -0400

    ENH: updated comments, default yamls, code
Merge pull request #326 from neurodebian/master

sloppy removal of  .bak files