snap command outputs unicode in publisher name even when locale is ascii

[Jason Hobbs]

With LANG=en_US, snap still outputs unicode characters in publisher's names in the info and install command outputs:
http://paste.ubuntu.com/p/rm7qTWZ548/

This is not true for unicode characters that snap itself generates, like the arrows in the version list and checkmark next to the publisher's name:
http://paste.ubuntu.com/p/mtW5M3Y5sM/

This causes problems when client programs try to decode output and expect to only see ascii characters; see bug 1819231.