Add additional fields of interest.

[Uberi]

Ref: https://bugzilla.mozilla.org/show_bug.cgi?id=1250889

[vitillo]

See comments in #31.

[Uberi]

Changes:

• Cherry-picked "Implement code review feedback" from fix-dates
• Update Fix dates with weird time zones. #31

[vitillo]

Looks good, I am waiting for @mreid-moz to comment on the bug.

[vitillo]

"The web server that receives Telemetry submissions stores the actual DNT header
value the client sends. This is more comprehensive than the DNT_USAGE
histogram, because it is included for all document types (even ones without
histograms), and that histogram is only being collected for clients who opt in
to extended telemetry. "

[Uberi]

The latest commit adds this field. dnt_header will be either the string 0, 1, or some other unknown value. As a result, it's a string. This field doesn't seem to be present in most telemetry pings from the pipeline.

[vitillo]

Looks good, thanks.