Added helper to set outpoint index.
Added helper to set outpoint index.

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