Added b2g-inbound support.

ex:
{
  "account": "",
  "password": "",
  "download_home": "inbound",
  "base_url": "https://pvtbuilds.mozilla.org/pvt/mozilla.org/b2gotoro/tinderbox-builds/",
  "build_id_format": "/{year}{month}{day}{hour}{min}{sec}/"
}