Optionally use setImmediate instead of nextTick in middleware

src/listener.coffee

@@ -73,7 +73,7 @@ class Listener
         # Yes, we tried to execute the listener callback (middleware may
         # have intercepted before actually executing though)
         if cb?
-          process.nextTick -> cb true
+          Middleware.ticker -> cb true
 
       response = new @robot.Response(@robot, message, match)
       middleware.execute(

src/middleware.coffee

@@ -1,6 +1,9 @@
 async = require 'async'
 
 class Middleware
+  # We use this recursively, and using nextTick recursively is deprecated in node 0.10.
+  @ticker: if typeof setImmediate is "function" then setImmediate else process.nextTick
+
   constructor: (@robot) ->
     @stack = []
 

src/robot.coffee

@@ -319,7 +319,7 @@ class Robot
             anyListenersExecuted = anyListenersExecuted || listenerExecuted
             # Defer to the event loop at least after every listener so the
             # stack doesn't get too big
-            process.nextTick () ->
+            Middleware.ticker () ->
               # Stop processing when message.done == true
               cb(context.response.message.done)
         catch err