EDXAPP_DJFS needs to be in YAML style?

Perhaps I'm just misunderstanding something, but the bash-style variable here appears to be incorrect, and it definitely caused an error for me, which went away after applying this change. See [this comment](https://github.com/edx/configuration/commit/96223cf48ad5abe4c8e477b1e76172af46d19966#commitcomment-9096894) for details on the error.