Add missing callback

Author: braydonf

lib/network/renter.js

@@ -64,7 +64,7 @@ inherits(RenterInterface, Network);
  * @param {Contract} contact - The contact to publish the contract
  * @param {Contract} contract - The storage contract to publish
  */
-RenterInterface.prototype.publishContract = function(contact, contract) {
+RenterInterface.prototype.publishContract = function(contact, contract, callback) {
   assert(contact instanceof Contact, 'Invalid contact supplied');
   assert(contract instanceof Contract, 'Invalid contract supplied');