Symbols do not respond to #sub
Ruby version matches 1.9.x or higher

I see no reason not to support UTF-8 moving forward, since that is now the
de-facto encoding in ruby.

Honestly, I don't see why this module needs to exist, other than to provide
support for ruby's earlier poor handling of character encodings.
Merge pull request #9 from nearbuy/master

Fix instance_variable#sub for ruby 1.9