* **Update:** The JSON data format is changed to the following format::

  tasks = {
      'keys' : [key1, key2, ...., keyN]
      'data' : [
          [task1.key1, task1.key2, ....., task1.keyN],
          [task2.key1, task2.key2, ....., task2.keyN],
          ...
          [taskN.key1, taskN.key2, ....., taskN.keyN],
      ]
  }

  This is much more compact then the original format, because the key names are
  not repeated over and over again, causing a compression ratio of roughly 3.5
  over the original format.