[FEATURE] Refresh Locks

[aikar]

What / Why

Requesting that lock staleness always be checked by mtime for all platforms, and the ability to keep a lock refreshed by routinely touching it.

Example

lockfile.lock(file, {stale: 30000, refresh: 1000, retry: 1000*60}, (err) => {

});

While the lock is open routinely do fs.touch, then mtime (as used by windows) will recognize the lock is not stale. Unlock should then stop the active timer.

[aikar]

Oh I see #12 is essentially this, just worded differently.