Remove the lock when we read or move the sqlite files.
    
    Since the cronjob never writes on the sqlite files that
    are used by the web server we don't need to protect these.
    The cronjob moving the file should be safe and at worst
    could result in a request failing during the move.
    
    Fixes #85
    
    Signed-off-by: Clement Verna <cverna@tutanota.com>