Removing a repetitive comment and removing a deprecation warning.

The comment on the +env_config+ method is repetitive, likely to get
outdated, and provides no useful information which cannot be gleamed
from the code. I'm therefore removing it. I'm also refactoring the check
for the presence of a secret_token in the configuration.

railties/lib/rails/application.rb

@@ -119,32 +119,9 @@ def key_generator
 
     # Stores some of the Rails initial environment parameters which
     # will be used by middlewares and engines to configure themselves.
-    # Currently stores:
-    #
-    #   * "action_dispatch.parameter_filter"             => config.filter_parameters
-    #   * "action_dispatch.redirect_filter"              => config.filter_redirect
-    #   * "action_dispatch.secret_token"                 => config.secret_token
-    #   * "action_dispatch.secret_key_base"              => config.secret_key_base
-    #   * "action_dispatch.show_exceptions"              => config.action_dispatch.show_exceptions
-    #   * "action_dispatch.show_detailed_exceptions"     => config.consider_all_requests_local
-    #   * "action_dispatch.logger"                       => Rails.logger
-    #   * "action_dispatch.backtrace_cleaner"            => Rails.backtrace_cleaner
-    #   * "action_dispatch.key_generator"                => key_generator
-    #   * "action_dispatch.http_auth_salt"               => config.action_dispatch.http_auth_salt
-    #   * "action_dispatch.signed_cookie_salt"           => config.action_dispatch.signed_cookie_salt
-    #   * "action_dispatch.encrypted_cookie_salt"        => config.action_dispatch.encrypted_cookie_salt
-    #   * "action_dispatch.encrypted_signed_cookie_salt" => config.action_dispatch.encrypted_signed_cookie_salt
-    #
     def env_config
       @app_env_config ||= begin
-        if config.secret_key_base.blank?
-          ActiveSupport::Deprecation.warn "You didn't set config.secret_key_base. " +
-            "Read the upgrade documentation to learn more about this new config option."
-
-          if config.secret_token.blank?
-            raise "You must set config.secret_key_base in your app's config."
-          end
-        end
+        validate_secret_key_config!
 
         super.merge({
           "action_dispatch.parameter_filter" => config.filter_parameters,
@@ -314,5 +291,11 @@ def build_original_fullpath(env) #:nodoc:
         "#{script_name}#{path_info}"
       end
     end
+
+    def validate_secret_key_config! #:nodoc:
+      if config.secret_key_base.blank? && config.secret_token.blank?
+        raise "You must set config.secret_key_base in your app's config."
+      end
+    end
   end
 end