Binary timestamp in backup_information.yml

Created by: abalkin

From tmp/backups/backup_information.yml:

:db_version: '20130410175022'
:backup_created_at: !binary |-
  MjAxMy0wNS0wNiAwNDowMToxMSAtMDQwMA==
:gitlab_version: e36372efd87ca488ea2747c0a0b18deb1fef2efe
:tar_version: tar (GNU tar) 1.23

The binary data in backup_created_at is simply 2013-05-06 04:01:11 -0400. I think this should be encoded as canonical YAML timestamp.

I don't know YAML specs well enough to say whether backup_information.yml is valid, but PyYAML does not accept it unless I change !binary tag to !!binary.