httpServer doesn't stop on ^C

[ulidtko]

This tool is clearly intended for command-line usage, but doesn't react to SIGINT properly.

So to stop snowboard -w http doc/myapi.md, the user has to do the CtrlZ, kill %1, fg dance; or perhaps something else involving kill in another terminal.

Instead, the http server should stop gracefully in response to the INT signal.

[subosito]

Closing this as ^C is working as expected.