This worked for me in Mavericks, probably works for earlier versions as well:
Open the Terminal
write this:
defaults write com.apple.Finder AppleShowAllFiles YES
and intro.
Now refresh the Finder: right-click on the Finder icon and select “refresh”
Thank you Mikesel for the explanation: http://www.mikesel.info/show-hidden-files-mac-os-x-10-7-lion/
