Upgrade image_optim dependency to 0.14.0

Change-Id: Id935cbcf5597b86b068a53f3af8535891cac386b
Reviewed-on: http://gerrit.causes.com/40841
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>

Author: sds

overcommit.gemspec

@@ -28,7 +28,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency             'childprocess', '>= 0.5.1'
 
-  s.add_development_dependency 'image_optim', '~> 0.13.0'
+  s.add_development_dependency 'image_optim', '~> 0.14.0'
   s.add_development_dependency 'rspec', '~> 3.0'
   s.add_development_dependency 'rubocop', '0.24.1' # Pin for Travis builds
 end