Revert "Bump rubygems version to 1.8.13"
Revert "Bump rubygems version to 1.8.13"

This reverts commit 8ae4e79122ae31db12ea21591fdf70b27521b4c6.

1337807/rubygems.org,square/rubygems.org,square/rubygems.org,1337807/rubygems.org,square/rubygems.org,rubygems/rubygems.org-backup,rubygems/rubygems.org-backup,rubygems/rubygems.org-backup,1337807/rubygems.org