Multilingual support for sign languages

[joemull]

User story

As an editor of a journal that publishes articles in multiple sign languages (DSDJ), I need to be able to encode more languages than just sgn ("sign languages"). These are the ones I need most:

• American Sign Language - ase
• International Sign - ils
• Swedish Sign Language - swl
• French Sign Language - fsl
• Italian Sign Language - ise
• Japanese Sign Language - jsl

Proposed solution

Support the full range of ISO-639-3 using Django Languages Plus.

Alternatives

Add just the requested languages to our current hard-coded list of choices.

Context

Freshdesk 8127