custom exchange name and options on bus.publish

allows to specify custom exchange name and options for pub/sub events
var bus = require('servicebus').bus({exchangeName: ‘custom-exchange’,
exchangeOptions: {durable:false, autoDelete:true, topic:’fanout’}});
Merge pull request #22 from ThibaultLaurens/feature/custom-exchange

custom exchange name and options on bus.publish
bumping version