async.parallel.js

// Implement async.parallel

// It should take: 1. An array of asynchronous functions, 2. A final callback 
// It should run all of the functions in parallel (just like in the ajax exercise)
// When all the calls are complete, it should call finalCallback with an array of the results from each call
// If there is any error, it should call finalCallback with the first error that comes from any of the functions
// It should only call finalCallback *one* time, either with an error, or with an array of results

async.parallel = function(functions, finalCallback) {

}

// Example call:

async.parallel([
  
  function(callback) {
    // do something then call callback
  },
  
  function(callback) {
    // do something then call callback
  },
  
  function(callback) {
    // do something then call callback
  }
  
], function(err, results) {

  // this final callback should be called when all of the previous functions completed, or one of them errored out
});