Revert "when checking for pubsub use a Set and O(1) #member? instead …

…of O(n) #include? on an Array"

It such a micro-optimization that I don't think it justifies the loading of 'set' (https://gist.github.com/935775)

This reverts commit c1d45f3.

lib/em-hiredis.rb

@@ -1,6 +1,4 @@
 require 'eventmachine'
-
-require 'set'
 require 'uri'
 
 module EventMachine

lib/em-hiredis/client.rb

@@ -1,6 +1,6 @@
 module EventMachine::Hiredis
   class Client
-    PUBSUB_MESSAGES = Set.new(["message", "pmessage"])
+    PUBSUB_MESSAGES = %w{message pmessage}.freeze
 
     include EventMachine::Hiredis::EventEmitter
     include EM::Deferrable
@@ -54,7 +54,7 @@ def connect
           deferred = @defs.shift
           deferred.fail(reply) if deferred
         else
-          if reply && PUBSUB_MESSAGES.member?(reply[0]) # reply can be nil
+          if reply && PUBSUB_MESSAGES.include?(reply[0]) # reply can be nil
             kind, subscription, d1, d2 = *reply
 
             case kind.to_sym