[io]let all io randomness be related to time(0)

[tornadomeet]

related to #2968
let all randomness with seed be related to time(0)

if not related to time(0), then every time when rerun program the randomness is the same. this will fix it, but i'm not sure whether it will influence other part.
@tqchen @piiswrong

[winstywang]

We need to discuss the behavior of this change. This design is deliberated at the beginning since we could reproduce the results exactly if we run the same codes. But it certainly will repeat the randomness if the program terminates and rerun.

What are your opinions?
@tqchen @piiswrong @antinucleon

[tqchen]

I think we should keep this behavior for now, reproduciblity is quite important, we can, however, enable a global seed that can be seeded through some functions and allow user to pass in the time seed

[tornadomeet]

@tqchen @winstywang user can pass seed by itself indeed, but currently the seed option is only used in shuffle, i.e. rnd_, not used for any others image augmentation, i.e. prnds_.so should we bring in another seed in ImageRecParserParam(this may puzzled the user)? or change the code to make ImageRecParserParam and ImageRecordParam share the same seed?

[winstywang]

@tornadomeet Yes, we need that modification