Changed string ToLower to it's invariant version.

This fixes potential bugs when running this code in Turkey (and other countries with similar rules).
Example: If a class is named "Integer" it will become "integer" in most places, in a Turkish localized machine it will become "ınteger". (see: http://www.codinghorror.com/blog/2008/03/whats-wrong-with-turkey.html )