Fix ugly bug in bytes

Was harmless until we actually started to use the state when
decoupling randomkit's stream from torch's.
Decouple randomkit's stream from torch

This will allow us to better recouple them with the new
thread-safe state structure in torch's RNG.
Use totem instead of torch.Tester

For dev purpose only, until totem is published.
Tests pass. Could do with an api tidy.
Don't need special method for a generator
Merge branch 'torch_RNG_threadsafety' into v0.1

This is compatible with Torch from commits
https://github.com/torch/torch7/commit/cfaebfb94fe831154d39714cc3788d3d3022f9ef
onwards.