Active Resource doesn't follow Rails versions. Keep it lower.

Author: kaspth

rails-observers.gemspec

@@ -23,6 +23,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'activerecord',   '>= 4.2'
   s.add_development_dependency 'actionmailer',   '>= 4.2'
   s.add_development_dependency 'actionpack',     '>= 4.2'
-  s.add_development_dependency 'activeresource', '>= 4.2'
+  s.add_development_dependency 'activeresource', '>= 4.0'
   s.add_development_dependency 'sqlite3',        '>= 1.3'
 end