Update image_optim dependency 0.9.1 -> 0.10.2

Change-Id: Ic37a28ce168ba01984290c1d5ddece6015f23331
Reviewed-on: https://gerrit.causes.com/33807
Tested-by: Joe Lencioni <joe.lencioni@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>

Author: lencioni

overcommit.gemspec

@@ -22,5 +22,5 @@ Gem::Specification.new do |s|
             Dir['config/*.yml']
 
   s.add_development_dependency 'rspec', '2.14.1'
-  s.add_development_dependency 'image_optim', '0.9.1'
+  s.add_development_dependency 'image_optim', '0.10.2'
 end