Add json serialization support

eg:

OAuth::RequestToken.class_eval do
def to_json(*a)

puts 'to_json called in RequestToken'

    {
            'json_class'   => self.class.name,
            'data'         => instance_values
    }.to_json(*a)
end

end

OAuth::RequestToken.instance_eval do

def json_create(o)
    consumer = OAuth::Consumer.new(o['data']['consumer']['key'], o['data']['consumer']['secret'], o['data']['consumer']['options'])
    OAuth::RequestToken.from_hash(consumer, o['data']['params'].update({:oauth_token=>o['data']['params']['oauth_token'], :oauth_token_secret=>o['data']['params']['oauth_token_secret']}))
end

end

OAuth::AccessToken.class_eval do
def to_json(*a)

puts 'to_json called in RequestToken'

    {
            'json_class'   => self.class.name,
            'data'         => instance_values
    }.to_json(*a)
end

end

OAuth::AccessToken.instance_eval do

def json_create(o)
    consumer = OAuth::Consumer.new(o['data']['consumer']['key'], o['data']['consumer']['secret'], o['data']['consumer']['options'])
    OAuth::AccessToken.from_hash(consumer, o['data']['params'].update({:oauth_token=>o['data']['params']['oauth_token'], :oauth_token_secret=>o['data']['params']['oauth_token_secret']}))
end

end