Fix encoding

While using with rails 3:
```
SyntaxError: .../vendor/bundle/gems/rchardet-1.3.1/lib/rchardet/universaldetector.rb:39: invalid multibyte escape: /[\x80-\xFF]/
from .../vendor/bundle/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
```