Added json dependency for Ruby 1.8 and below
Added json dependency for Ruby 1.8 and below

jarthod/pusher-ruby-client,rkh/pusher-ruby-client,Intrepidd/pusher-ruby-client,ericzinnikas/pusher-ruby-client,preplay/pusher-ruby-client,machadolab/pusher-ruby-client,Juanmcuello/pusher-ruby-client,mediaslave24/pusher-ruby-client,fukayatsu/pusher-websocket-ruby,emnl/pusher-ruby-client,pusher-community/pusher-websocket-ruby