Devise locales

ok we're out-sourcing our devise translations to the devise-i18n gem 

What I've done is added several commits so y'all can see the changes that are happening:
- The second commit *'...diff view'*   shows what the gem is adding in (I pulled the raw files).
I've looked at the diffs, they're mainly a standardisation of yml order. There is at least one deletion
see [this note](https://github.com/loomio/loomio/commit/feb5c47d406605ba2256adcb130ed7295802d8b9#diff-64563dc84b38c7a7713d0e953f1f59d5L13) - wait for slow load - about the key `invalid_token`. 
Would like an opinion on it

- The final commit removes the `devise.*.yml`, so we're just left with the gem


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@novicaz this is your translation work about to go live. 
Note that it's also folded into that gem you submitted to now, so everyone will have access to your work!