Improved Link Reporting + New search sources

Link source now returns additional host parameter in order to use that to split network/referral sources by the host of the referral link.

BEFORE

{
  "referrer": {
    "type": "link",
      "from": "from",
      "link": "link",
  }
}

AFTER

{
  "referrer": {
    "type": "link",
      "from": "from",
      "link": "link",
      "host": "host"
  }
}

This also includes a new list of search sources taken from Google Analytics Help page.