[Fix #2068] Use mail templates from application rather than devise
[Fix #2068] Use mail templates from application rather than devise

`default template_path:` was the documented way, but wasn’t working
(and there was no hint in the source code of Devise that it could
work)

Therefore, let’s override `template_paths` instead and stop worrying

sgmap/tps,sgmap/tps,sgmap/tps