Relaxed unnecessarily strict rack dependency to ~> 1.2

[JammyStuff]

oauth2 uses 2 methods in the Rack gem, both of which are located in lib/rack/utils.rb. The comparison at rack/rack@2ed5157...e932c58 shows that the only changes between 1.2 and 1.4 in these methods are performance improvements or security updates which are not relevant here, as we are not acting as a server.

[sferik]

Is there some particular reason why you can't upgrade from 1.2 to 1.4?

[JammyStuff]

We've got a pretty large Rails app, and each new Rails release seems to break parts of it. We fix those parts, but it takes time. Because of that, even though we're catching up, we're currently running rails 3.0.14. actionpack 3.0.14 has a requirement for rack 1.2.5, so that's what we're currently running. Even when we roll out Rails 3.1, which will be very soon, actionpack is going to be requiring rack 1.3.2