Seeming fix for JSON decoding errors in transaction log.

This corresponds with the patch in the `json-corruption-patch` branch of the server, which will have to be manually applied.
Until the server starts sending things in a singular JSON dictionary (e.g. when we can merge the patch on the server), it's not really safe to apply this because then there will be a problem between versions.

This fixes the issue mentioned on bloocoin/bloocoin-server#1.