Add channel generator feature

Author: vivekmiyani

features/generator_specs/channel_specs.feature

@@ -0,0 +1,31 @@
+Feature: Channel generator spec
+
+    Scenario: Channel generator
+        When I run `bundle exec rails generate channel group`
+        Then the features should pass
+        Then the output should contain:
+          """
+                invoke  rspec
+                create    spec/channels/group_channel_spec.rb
+                create  app/channels/group_channel.rb
+             identical  app/javascript/channels/index.js
+             identical  app/javascript/channels/consumer.js
+                create  app/javascript/channels/group_channel.js
+          """
+
+    Scenario: Channel generator with customized `default-path`
+        Given a file named ".rspec" with:
+          """
+          --default-path behaviour
+          """
+        And I run `bundle exec rails generate channel group`
+        Then the features should pass
+        Then the output should contain:
+          """
+                invoke  rspec
+                create    behaviour/channels/group_channel_spec.rb
+                create  app/channels/group_channel.rb
+             identical  app/javascript/channels/index.js
+             identical  app/javascript/channels/consumer.js
+                create  app/javascript/channels/group_channel.js
+          """