Sanitize logs in go-updater

[jumde]

Current log format:

time="2019-02-27T05:31:20Z" level=info msg="request complete" X-Forwarded-For="73.121.137.159, 157.52.75.67" X-Forwarded-Host=go-updater.brave.com http_method=POST http_proto=HTTP/1.1 http_scheme=http remote_addr=73.121.137.159 req_id=160e79999b4f/31vUVbNUag-001580 resp_bytes_length=2954 resp_elapsed_ms=0.356856 resp_status=200 uri="http://go-updater.brave.com/extensions" user_agent="Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.80 Safari/537.36"

• Sanitize logs to remove IP addresses
• Limit retention period for logs to 3 days.

[jumde]

@bbondy @tomlowenthal - let me know if you have any concerns. cc: @hspencer77

[bbondy]

sgtm

[tildelowengrimm]

Perf imo tbh.