Update aws-sdk and cucumber gem versions.

Turns out that aws-sdk v2 isn't backwards compatible in the slightest,
so we should cap that at v1. And cucumber 1.3.17 was giving issues with
ruby 2.2.0. So let's update those.

paperclip.gemspec

@@ -32,9 +32,9 @@ Gem::Specification.new do |s|
   s.add_development_dependency('rspec')
   s.add_development_dependency('appraisal')
   s.add_development_dependency('mocha')
-  s.add_development_dependency('aws-sdk', '>= 1.5.7')
+  s.add_development_dependency('aws-sdk', '~> 1.5')
   s.add_development_dependency('bourne')
-  s.add_development_dependency('cucumber', '~> 1.3.11')
+  s.add_development_dependency('cucumber', '~> 1.3.18')
   s.add_development_dependency('aruba')
   s.add_development_dependency('nokogiri')
   # Ruby version < 1.9.3 can't install capybara > 2.0.3.