Have the 5 most common currencys already stored

[kosturm]

Maybe have most common currencies already stored.

[finnharbeke]

i recently changed currencies to be user-bound, hence there are no currencies at the start. but i don't exactly remember why i changed them to be user-bound, i don't think anyone is in need of creating currencies that don't exist...

• i'll either go back to universal currencies (accounts from different users with the same currency have the same currency_id)
• or just add some currencies upon registration of the user, e.g. usd, eur, chf etc