Add addressable requirement to gemspec

Author: mscoutermarsh

htmlcsstoimage.gemspec

@@ -24,6 +24,7 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_dependency "httparty", "> 0.10"
+  spec.add_dependency "addressable", "> 2.5.0"
   spec.add_development_dependency "bundler", "> 2.0"
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "rspec", "~> 3.0"