Update image_optim dependency 0.12.0 -> 0.13.0

Changes:

  toy/image_optim@70ec2ed...8fe5473

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

Author: lencioni

overcommit.gemspec

@@ -29,5 +29,5 @@ Gem::Specification.new do |s|
   s.add_dependency             'childprocess', '>= 0.5.1'
 
   s.add_development_dependency 'rspec', '2.14.1'
-  s.add_development_dependency 'image_optim', '0.12.0'
+  s.add_development_dependency 'image_optim', '0.13.0'
 end