relax rails

Author: janbiedermann

hyperloop.gemspec

@@ -27,5 +27,5 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'opal-rails', '~> 0.9.3'
   spec.add_dependency 'react-rails', '>= 2.3.0', '< 2.5.0'
   spec.add_dependency 'mini_racer', '~> 0.1.14'
-  spec.add_runtime_dependency 'rails', '~> 5.1.4'
+  spec.add_runtime_dependency 'rails', '=> 4.0.0'
 end