Add Japanese translations of the generation names, thanks to @SethETaron. I think this marks our first unofficial Japanese translation. 🎉
Also, fix some issues with Gen VII:
* generation names were missing for every language
* the identifier was incorrect — it was sun-moon instead of generation-vii
Fixes#250, #251, and #252.
Generation VI doesn't have a canonical pokedex (it has three). We don't
use this anywhere and as far as i can tell we never have. We can revive
it in another form if and when we find we need it.
Conflicts:
pokedex/data/csv/generations.csv
pokedex/db/tables.py
