Add special case for FxOS FTU pings (bug 1210894)

[mreid-moz]

Most FTU pings are being sent to the error stream due to missing the
expected 'info' section of the payload. These pings can be identified
by 'ver = 3' (this is either 1 or 2 for normal old-style Telemetry
records). Example FTU v3 doc:

{
  "ver": 3,
  "screenHeight": 1080,
  "screenWidth": 1920,
  "devicePixelRatio": 1,
  "locale": "en-GB",
  "pingID": "deadbeef-0000-0000-95b0-f387d780548f",
  "activationTime": 1449740000000,
  "deviceinfo.os": "2.1.0.0",
  "deviceinfo.software": "Boot2Gecko 2.1.0.0",
  "deviceinfo.platform_build_id": "20151210052433",
  "deviceinfo.platform_version": "34.0",
  "deviceinfo.product_model": "PTV-TX-58DX780E",
  "deviceinfo.firmware_revision": "0001",
  "deviceinfo.hardware": null,
  "app.update.channel": "default",
  "pingTime": 1449740000000
}

[mreid-moz]

It's a little easier to see what actually changed if you stick ?w=1 on the end of the diff URL