Update image_optim dependency 0.12.0 -> 0.13.0

Changes:

  https://github.com/toy/image_optim/compare/70ec2ed18aebc1cc07038e0b0c7494f2b23e4fec...8fe5473e2a5aa23db9121dd19b3a464c8323a443

Change-Id: Ifc992739207715ed4ca136bf2097551f0bc83b6b
Reviewed-on: http://gerrit.causes.com/36959
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>