Fix error being swallowed up

[glyphCezilleSantillan]

Also for #76 . The mysteriously vanishing error was being swallowed up by this code:

reject = _.once((function (oldReject) {
    return function () {
      oldReject();
      resolve = function () {};
    };
})(reject));

All it needed was the error parameter:

reject = _.once((function (oldReject) {
    return function(err) {
        oldReject(err);
        ...

However, Underscore's _.once handles this for us already, so I just changed it to

 reject = _.once(reject);

[glyphCezilleSantillan]

However, the initial code also did the same thing -- the resolve and reject were called only once, and actually overwritten with noop. Calling once did the same thing, only shorter. Perhaps the entire code block could be removed, since, like you said, promises get resolved/rejected only once?

[danjenkins]

What do you think @chadxz / @samuelg ? From what I understand, this is the right course of action

[samuelg]

Published v1.1.1 to npm.

[danjenkins]

thanks @samuelg ! I was walking the dog when @chadxz approved otherwise I would have released the changes :)