Add a negated balance entry.

The reason for this is that with OKQ8-VISA, "Saldo" (balance) means
"used credit" which is kind of backwards compared to how most other
accounts work.
New bank: Akelius Spar

This is pretty much a search-replace change of the Akelius Invest
support as they are very similar.
Display account type instead of numeric ID

Instead of the numeric ID of the account, use its account type.
Before: 98123621
After: Investeringssparkonto
Merge pull request #202 from Tuxie/master

Add a negated "Saldo" to OKQ8-VISA.