delete custom Enumerable#group_by
while i'm at it, :fire: other unused monkey patches
replace uses of OrderedHash with just a regular hash
delete all these method definitions
AS::OrderedHash#to_yaml is just completely broken

irb(main):004:0> ActiveSupport::OrderedHash["a",1,"b",2].to_yaml
ArgumentError: wrong number of arguments (2 for 0)
	from /Users/charlie/github/github/vendor/gems/2.0.0/ruby/2.0.0/gems/activesupport-2.3.14.github25/lib/active_support/ordered_hash.rb:16:in `block in to_yaml'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/deprecated.rb:19:in `call'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/deprecated.rb:19:in `block in quick_emit'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:449:in `dump_coder'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:126:in `accept'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:92:in `push'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych.rb:244:in `dump'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/core_ext.rb:14:in `psych_to_yaml'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/deprecated.rb:21:in `quick_emit'
	from /Users/charlie/github/github/vendor/gems/2.0.0/ruby/2.0.0/gems/activesupport-2.3.14.github25/lib/active_support/ordered_hash.rb:15:in `to_yaml'
	from (irb):4
	from script/console:56:in `<main>'

irb(main):005:0> YAML.dump(ActiveSupport::OrderedHash["a",1,"b",2])
ArgumentError: wrong number of arguments (2 for 0)
	from /Users/charlie/github/github/vendor/gems/2.0.0/ruby/2.0.0/gems/activesupport-2.3.14.github25/lib/active_support/ordered_hash.rb:16:in `block in to_yaml'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/deprecated.rb:19:in `call'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/deprecated.rb:19:in `block in quick_emit'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:449:in `dump_coder'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:126:in `accept'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:92:in `push'
	from /Users/charlie/.rubies/ruby-2.0.0-github/lib/ruby/2.0.0/psych.rb:244:in `dump'
	from (irb):5
	from script/console:56:in `<main>'
in fact we don't even need to bother creating a new class
Let's just use Psych::Omap for YAML omaps
Merge pull request #20 from github/dont-use-ordered-hash

Replace use of OrderedHash with regular hashes