Lock addressable version to 2.4

2.5.0 uses publix_suffix which requires ruby > 2.0

Author: vivangkumar

pusher.gemspec

@@ -21,6 +21,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rspec", "~> 3.0"
   s.add_development_dependency "webmock"
   s.add_development_dependency "em-http-request", "~> 1.1.0"
+  s.add_development_dependency "addressable", "=2.4.0"
   s.add_development_dependency "rake", "~> 10.4.2"
   s.add_development_dependency "rack", "~> 1.6.4"
   s.add_development_dependency "json", "~> 1.8.3"