re-add making binaries executable.

fixes what was originally broken in #996b517
because it was trying to do a for-loop with
a variable named file that didnt exist.

this doesnt even actually quite work yet because
of the copy function not having a callback. Soon™.
Add callback to creator.copy to allow chmodding bin/hubot
Merge pull request #491 from brntbeer/copy-script-file-permission

Copy script file permission