merge revision(s) r45221: [Backport #9798]

	* ext/psych/lib/psych/visitors/yaml_tree.rb: support dumping Encoding
	  objects.

	* ext/psych/lib/psych/visitors/to_ruby.rb: support loading Encoding
	  objects.

	* test/psych/test_encoding.rb: add test

	* ext/psych/lib/psych.rb: add version


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@45811 b2dd03c8-39d4-4d8f-98ff-823fe69b080e