The -start-vpn flag can be set to on or off to turn the vpn on or off
just after launching bitmask-vpn. So it doesn't depend on the status of
the vpn of the last run.

- Resolves: #114

Make possible to disable the autostart configuration for the next run. I
can be done by configuring "DisableAustostart" to true in the
systra.json or by passing the '-disable-autostart' flag to the binary.

To make that possible I have rework how the Config struct work
separating the file configuration with the runtime configuration.

- Resolves: #100

Let's use a more structured folder system:
https://github.com/golang-standards/project-layout

- Resolves: #99