Fix post graphite task

The relevant commit is the first one. It's weird, but I tried to use the gem in a deploy and it doesn't work. Maybe it's something related with versions. I'm using capistrano 3.2.1 and rake 10.3.2. My commit is a fix for these, but not sure if it works with previous versions.
Second commit is just a style thing, you can ignore it if you don't like it.