Fix sinatra base

[akatz]

fixes for issue #14

[ejschmitt]

thanks

[ankane]

Hey Erick,

Please bump the version number of the gem. This commit fixes a huge, unobvious issue.

When sinatra is required, this line is executed in the main space.
https://github.com/sinatra/sinatra/blob/master/lib/sinatra/main.rb#L30

Here's the issue we ran into with Rails 3.2.12 and scopes. (not_found is a scope on the Item model)

# works - returns models
Item.not_found

order = Order.find(1)
order.items.not_found # => returns 404 instead of models

The not_found method is delegated to the sinatra application rather than the rails activerelation after we installed this gem. This commit fixes the problem.