thoughtbot/paperclip — pull request #1505 by boone (2014-04-06 16:24:38+00:00)
Title: Document requirement for file command.

I was getting the failure "File has an extension that does not match its contents". In my case, it turns out that the `file` command was not installed by default on my Centos 6 VPS. I added a note about the requirement for this command in the Readme.