Make open source the default, and check for sass instead

lib/bootstrap.rb

@@ -1,5 +0,0 @@
-module Bootstrap
-  def self.oss_config?
-    ENV.fetch("OSS_CONFIG", "") != "" || !File.directory?(File.expand_path("../gems/fizzy-saas", __dir__))
-  end
-end

lib/fizzy.rb

@@ -0,0 +1,5 @@
+module Fizzy
+  def self.saas?
+    defined?(Fizzy::Saas::Engine)
+  end
+end