Support emoji import in anorak/boots importers

[tienne-B]

With TabbycatDebate/tabbycat#200, emoji are randomly assigned to all imported teams, overriding emojis set if an emoji field is found in the import file. Ideally, the importer should keep the emojis. A slight complication would be to assure the emoji is a valid choice, and to strip all modifiers.

[czlee]

I guess this is moot now, or should be moved to the new importers repo?