bumping version
Merge branch 'master' of github.com:tenderlove/psych

* 'master' of github.com:tenderlove/psych:
  backport r48512 from ruby/ruby trunk.
  Add changelog for 2a4d9568f7d5d19c00231cf48eb855cc45ec3394
  backport r48214 from ruby/ruby trunk.
  Allow dumping any BasicObject that defines #marshal_dump or #marshal_load