Callbacks for response status codes

[kaiwren]

API to allow callbacks based on the HTTP status code of a response. Should support ranges. Tentatively something like
'http://ooga.com/foo'.to_uri(:on_respose_code => {
401 => lambda {|response| raise UnauthorizedException},
500..599 => lambda do |response|
Wrest.logger.error response.body
raise ServerDiedException
end
}
).get.deserialise

This is closely related to feature request #49.

[jasim]

Using option :callback instead of :on_response_code.

[jasim]

kaiwren@f7051ac