placeholder `%files` should not use a trailing slash

[oxyc]

fsi master*: robo rsync:pull @production:%files/sites/16
?  Dry run does currently not work, do you wish to continue with the real command? (y/n) y
 [Generoi\Remote\RsyncAlias] Running rsync --progress --human-readable --rsh 'ssh -o ForwardAgent=yes -o "..."' --recursive --archive --compress --exclude .git --exclude .svn --exclude .hg --checksum '....:/home/www/deploy/deploy/current/web/app/uploads//sites/16' /Users/oxy/Projects/Genero/fsi/web/app/uploads//sites/16