Fix the spelling of the word replacment in the file helper

Very minor change, but the spelling bothered me. :)
Add myself as an author.
Merge pull request #104 from jhubert/typo-fix-replacments

Fix the spelling of the word replacment in the file helper
Merge branch 'master' into stable
Merge branch 'stable' of github.com:Compass/compass-rails into stable
Merge branch 'stable'