This allows for shared hledger installations, where the web interface is
available via network and multiple user share a SSH access to the
hledger user.
Also added `--serve` to the CLI options, as hledger-web tries to open a
webbrowser otherwise:
hledger-web: xdg-open: rawSystem: runInteractiveProcess: exec: does not
exist (No such file or directory)
Co-authored-by: Aaron Andersen <aaron@fosslib.net>
