Fixes 20130814130142_remove_documents.rb

The down migration used i18n that was not available as well as using
table_exists w/o the question mark.
Merge remote-tracking branch 'opf/feature/rails3' into feature/fixed-20130814130142

Conflicts:
	doc/CHANGELOG.md
Merge pull request #368 from opf/feature/fixed-20130814130142

Fixes 20130814130142_remove_documents.rb