Implement a statistics HTTP server

1. Not sure what this is?
2. This is where I intended to put the comment I had elsewhere...  this is a variable definition, and can't be in a .h file...!
3. 4? 86400? (Yes, I know it's "seconds per day" but no magic numbers!  and why not `std::chrono::day (1)`?  or `std::chrono::hour (24)`)
4. Spaces before argument lists please - the space after seconds in `std::chrono::seconds (1)`