Accept a small compression loss is in exchange for a fixed sized encoder
side buffering requirement.

subset1:
rans_base@2016-12-02T22:55:56.809Z -> rans_nsym@2016-12-02T22:58:19.859Z

    PSNR | PSNR Cb | PSNR Cr | PSNR HVS |   SSIM | MS SSIM | CIEDE 2000
  0.0304 |  0.0303 |  0.0305 |   0.0317 | 0.0312 |  0.0309 |     0.0301

Change-Id: I09dd143e4f1638b97dc9bba7023efa837a7d48c7