Notes on closing subcreddit:
This doesn't seem great. Would be slightly better if closed could be referenced
as true or false instead of '0' or '1' in the model. Testing this is a bit
messy, but Tiemcop makes it a bit better.
Notes on subcreddit validations:
This is still not ideal. For starters, from
http://guides.rubyonrails.org/active_record_validations.html:
"Note that some databases are configured to perform case-insensitive searches
anyway."
It also seems difficult to validate fields that are set in before_save since
validations occur before callbacks. Revisit this (perhaps friendly_id wll save
us).
