Add block number to the accounting index.
Add block number to the accounting index.

This allows us to sort transactions from multiple accounts without
retrieving any additional information from the database.

bitfloor/bitcoinjs-server,javascriptit/bitcoinjs-server,dazoe/bitcoinjs-server,dazoe/bitcoinjs-server,javascriptit/bitcoinjs-server,zhangweis/node-jds,zhangweis/node-jds,bitfloor/bitcoinjs-server,bankonme/bitcoinjs-server,bankonme/bitcoinjs-server,zhangweis/node-jds,bankonme/bitcoinjs-server,javascriptit/bitcoinjs-server,dazoe/bitcoinjs-server