exercism/exercism.io — pull request #1471 by stevenwu (2014-03-14 22:41:17+00:00)
Title: Do not save submission if it has no slug

This is what I have so far for #1463. ``Attempt#save`` returns ``false`` when you try to save a submission with no slug. Not sure if this should be an error message instead.

Currently, if a file has no file extension / language, there'll be an ``UnknownLanguage`` error on ``#save``.