install i18n before activerecord to avoid dependency bug

Currently we're running into trouble installing activerecord with Ruby 1.8.7 because of the following

activerecord -> activesupport -> i18n (bumps to 0.7.0) -> Ruby 1.9.3

We think this is a bug in the activesupport dependencies:
Maybe, 
i18n (>= 0.6.9, ~> 0.6)
should be
i18n (>= 0.6.9, ~> 0.6.0)