Added a generic error handler function for database queries.
Added a generic error handler function for database queries.

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