Implement better rate-limiting/retry logic

[GoogleCodeExporter]

The current crashpad_handler makes one upload attempt per hour. Any would-be 
upload attempts in excess of this are never attempted. Any failed upload is 
never retried.

This logic exactly matches the Mac Breakpad client as configured for use by 
Chrome, but it’s not elegant or flexible.

We should implement something better, possible with multiple stacked rules, like

limit 2 upload attempts within 2 hours
limit 6 upload attempts within 12 hours
initial retry attempt for a report is a 1 hour delay after initial upload 
attempt
subsequent retry attempts for a report back off by doubling the delay to a 
maximum delay of 8 hours
reports that failed to upload are retired after 48 hours

or something like that.

Original issue reported on code.google.com by mark@chromium.org on 26 Mar 2015 at 9:30