lib/deployer.js
function(target, source) {
    var skeys = _.keys(source);
    _.each(skeys, function(skey) {
      if (!target[skey]) {
        target[skey] = source[skey];
      }
    });
    return target;
  }
function(target, source) {
    var skeys = _.keys(source);
    _.each(skeys, function(skey) {
      if (!target[skey]) {
        target[skey] = source[skey];
      }
    });
    return target;
  }
merge in any properties to target that are excelusively only in source