Latest gems and fix a callback bug

.ruby-version

@@ -0,0 +1 @@
+2.1.5

Gemfile

@@ -2,3 +2,9 @@ source 'http://rubygems.org'
 gemspec
 
 gem 'cramp', github: "lifo/cramp"
+
+group :test do
+  gem 'rake'
+  gem 'puma'
+end
+

Gemfile.lock

@@ -0,0 +1,54 @@
+GIT
+  remote: git://github.com/lifo/cramp.git
+  revision: 60f6f30fe69fedd076ac7cb64f65ba8f382c8a67
+  specs:
+    cramp (0.15.4)
+      activesupport (~> 4.2.0)
+      eventmachine (~> 1.0.3)
+      faye-websocket (~> 0.9.2)
+      rack (~> 1.6.0)
+      thor (~> 0.19.0)
+
+PATH
+  remote: .
+  specs:
+    action_cable (0.0.1)
+      activesupport (~> 4.2.0)
+      cramp (~> 0.15.4)
+
+GEM
+  remote: http://rubygems.org/
+  specs:
+    activesupport (4.2.0)
+      i18n (~> 0.7)
+      json (~> 1.7, >= 1.7.7)
+      minitest (~> 5.1)
+      thread_safe (~> 0.3, >= 0.3.4)
+      tzinfo (~> 1.1)
+    eventmachine (1.0.4)
+    faye-websocket (0.9.2)
+      eventmachine (>= 0.12.0)
+      websocket-driver (>= 0.5.1)
+    i18n (0.7.0)
+    json (1.8.2)
+    minitest (5.5.1)
+    puma (2.10.2)
+      rack (>= 1.1, < 2.0)
+    rack (1.6.0)
+    rake (10.4.2)
+    thor (0.19.1)
+    thread_safe (0.3.4)
+    tzinfo (1.2.2)
+      thread_safe (~> 0.1)
+    websocket-driver (0.5.1)
+      websocket-extensions (>= 0.1.0)
+    websocket-extensions (0.1.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  action_cable!
+  cramp!
+  puma
+  rake

lib/action_cable/server.rb

@@ -11,7 +11,7 @@ module ActionCable
 
     class << self
       def register_channels(*channel_classes)
-        registered_channels.merge(channel_classes)
+        self.registered_channels += channel_classes
       end
     end