Remove workaround for Rails 2.x stuff

It is no longer needed since MarkUs does not run on Rails 2.x anymore.
Remove an unused code path

I seem to have forgotten this when doing the encoding upgrade.
Merge pull request #1528 from ferrous26/oops

Remove an unused code path
Merge pull request #1527 from ferrous26/dce2

Remove workaround for Rails 2.x stuff