allow Rails 4.x and 5.x

Author: syoder

kracken.gemspec

@@ -15,7 +15,7 @@ Gem::Specification.new do |s|
 
   s.files = Dir['{app,config,db,lib}/**/*', 'MIT-LICENSE', 'Rakefile', 'README.md']
 
-  s.add_dependency 'rails', '~> 5.0'
+  s.add_dependency 'rails', [">= 4.0", "< 6.0"]
   s.add_dependency 'omniauth', '~> 1.0'
   s.add_dependency 'faraday', '~> 0.8'
   s.add_dependency 'omniauth-oauth2', '~> 1.1'