bitmask-vpn installs a daemon called bitmask-helper
which exposes a http api to handle firewall up/down
and openvpn connect/disconnect (only in macos)

this daemon was listening on localhost, since it is
meant to be only accessible to local processes we'v
changed it to listen on a unix domain socket

using unix socket allows to apply file  permissions
and restrict access to the api to only the intended
user

cli (cmd/bitmask-helper/main.go and) and helpers (pkg/pickle/helpers.go)
were also fixed.

Multiple log levels are supported and can be set via env variable (LOG_LEVEL)
- trace (LOG_LEVEL=TRACE)
- debug (LOG_LEVEL=DEBUG)
- everything else: INFO

Signed-off-by: kali kaneko (leap communications) <kali@leap.se>

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