apps/nsq_to_file: add <PID> filename format tag
apps/nsq_to_file: supported rotate by size & interval

ADD:
--rotate-size=0,        rotate the file when it grow bigger than `rotate-size` bytes
--rotate-interval=0,    rotate the file every `rotate-interval` seconds
--max-revision=1000,    the max <REV> number

CHANGE:
1. rename <GZIPREV> to <REV> in filename format
2. `Sync` before `Close`