Fix RUBYLIB path for ruby >= 1.9

Apparently . was removed from the default RUBYLIB path between ruby 1.8
and 1.9. Do a little magic to make it work correctly. There's a more
"proper" change for this but the method call needed to make it work well
doesn't exist in ruby 1.8 apparently :-/

Signed-off-by: Andrew Grimberg <tykeal@bardicgrove.org>