Signed-off-by: Alexandre Derumier <aderumier@odiso.com>

Unlike flock, LockFile::Simple does not inherit locks to child process.
So we need to do the locking inside the child process.

Else the buttons are still functional, and the user can trigger
additional command (i.e. several restore processes).

Only test MD5 if status is active

Signed-off-by: root <aderumier@odiso.com>

The maxfiles flags is now a storage related flag. So we set that on
the storage definition, and removed it from the scheduled backup GUI.
We use '--remove 0' for 'Backup now', so the user need to remove
old backups himself.