implement "allow reboot" and use when necessary

[vdelendik]

let's parametrize vie env var possibility to send device to reboot when we definitely know that's the only applicable case for restoring device.
For example this one: zebrunner/appium#241

Also some cases exists on android. Btw, make sure we do automatic reboot at once and after that we just do exit 0 and require manual inspection to avoid reboots in permanent loop

[vdelendik]

also need a ticket for mcloud-agent. I'd suggest "allow_reboot" tag per each device to enable it only for problematic one.