Revert "fix access priorities of each level in LeveledOptions"

This reverts commit 15f0847.

Fixes #1200

lib/puma/configuration.rb

@@ -31,7 +31,7 @@ def shift
     end
 
     def [](key)
-      @set.reverse_each do |o|
+      @set.each do |o|
         if o.key? key
           return o[key]
         end

test/test_config.rb

@@ -56,17 +56,6 @@ def test_allow_users_to_override_default_options
     assert_equal 'bin/rails server', conf.options[:restart_cmd]
   end
 
-  def test_overwrite_options
-    conf = Puma::Configuration.new do |c|
-      c.workers 3
-    end
-    conf.load
-
-    assert_equal conf.options[:workers], 3
-    conf.options[:workers] += 1
-    assert_equal conf.options[:workers], 4
-  end
-
   private
 
     def with_env(env = {})