Currently any input is accepted for the language of a Gloss. We should restrict this in order to make it easier to re-use and to be able to do language fallbacks etc.
* I can not enter a language for a Gloss that is not in the list we validate against.
* I can enter any language that is on the list we validate against.
GIVEN I am on a Lexeme page
AND I edit a Gloss
WHEN I enter a language that is not considered valid
THEN the field is highlighted in red
AND the save button is grayed out
* Which list do we validate against?