Move language list into config
Don't use trail in stats pages
Delete unused method
Don't bother validating submission

Someone has to work pretty hard to submit something that's not a real
exercise, and if they do, then it's fine. It will simply not show up in
the nitpick lists. No great tradegy.
Delete unnecessary dependency in Completion
Delete unused method
Remove path from trail and curriculum
Delete unused methods in trail
Delete left-over class
Delete unused fixtures
Remove dependence on curriculum from Work
Remove reliance on curriculum in workload
Remove dependency on curriculum in seeds
Delete curriculum
Update contributing guide
Merge branch 'delete-curriculum'