Multicontainer OS version to Artik7

[pauldepraz]

UPDATE Mar. 23 2018 - They are working on it as stated on the link below. I will try to keep this updated for other with the same issue.

State update: Multicontainer

Hey @pauldepraz, v2.12.3 (which supports multicontainer) for the ARTIK 710 is currently up in our staging environment, we just need to run it through some tests and it should hopefully be out in production sometime next week.