Add rack-test dependency

Dependency needed for oauth rspec

Author: pcupueran

bitbucket_rest_api.gemspec

@@ -23,6 +23,7 @@ Gem::Specification.new do |gem|
   gem.add_dependency 'simple_oauth'
 
   gem.add_development_dependency 'rspec', '>= 0'
+  gem.add_development_dependency 'rack-test'
   gem.add_development_dependency 'webmock', '~> 1.8.0'
   gem.add_development_dependency 'vcr', '~> 2.2.0'
   gem.add_development_dependency 'simplecov', '~> 0.6.1'