Upgrade to Bluebird.js (core) for cancelable HTTP requests

[dustinlarimer]

• Import bluebird.core and update minifying task to reduce minified file size.
• Improve the query response mocking for ad-hoc queries, so that the original query body is returned in every case for downstream use. Eventually this will be handled universally by the API, but for now we're mocking it, with the saved-query response shape as a guide.

[dustinlarimer]

Example usage:

// assume var client = new Keen({ ... });
var req = client.query('count', {
    event_collection: 'pageviews',
    timeframe: 'this_14_days'
  })
  then(function(res){
    // handle res
  });

// Nevermind, close it down!
req.cancel();
// XHR request canceled