Convert response status to Integer with to_i method call

[andrykonchin]

The specification require response status to have only method to_i to convert it to Integer. Some middleware treat it as Integer itself.

Here was added explicit conversion to Integer.

Changes:

• fixed Rack::JSONP
• fixed Rack::RelativeRedirect
• fixed Rack::ResponseCache
• fixed Rack::TryStatic

[ioquatix]

@jeremyevans any thoughts on this? Should status actually be required to be an integer?

[jeremyevans]

This depends on the decision we make in rack/rack#1644. Under current SPEC, yes, to_i would be required for correctness. However, I think we should change SPEC. Non-integer status doesn't add value, IMO.

[rkh]

Made obsolete by rack/rack#1662.