Remove Windows-specific comments about gem install bundler

Now that we are recommending all attendees run `gem install bundler`
we keep the volume of text a little smaller. Also remove
somewhat odd reference to `production.rb`.

Author: tjgrathwell

sites/en/installfest/deploy_a_rails_app.step

@@ -91,7 +91,7 @@ gem install bundler
 bundle install --without production
     BASH
 
-    message "Again, wait for the console prompt, and look for the 'Bundle complete!' message just above.  If you are on Windows and you get the message 'The system cannot find the path specified.', then you need to first install Bundler. You can do this by typing `gem install bundler`. Once this finishes, then redo the `bundle install --without production` command.  If this fails, get a volunteer to help you edit `config/environments/production.rb` "
+    message "Again, wait for the console prompt, and look for the 'Bundle complete!' message just above."
   end
 
   step "Set the root route" do