support Rails 6

This copies some changes over from a previous attempt to support Rails 6
which is in the `rails6` branch.

Author: syoder

kracken.gemspec

@@ -22,7 +22,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'faraday', ['>= 0.8', '< 2.0']
   s.add_dependency 'omniauth', '~> 1.0'
   s.add_dependency 'omniauth-oauth2', '~> 1.1'
-  s.add_dependency 'rails', [">= 5.2", "< 6.0"]
+  s.add_dependency 'rails', [">= 5.2", "< 7.0"]
 
   s.add_development_dependency 'pry'
   s.add_development_dependency 'pry-nav'

lib/kracken/rspec.rb

@@ -46,6 +46,7 @@ def current_user
 module Kracken
   module Controllers
     module Authenticatable
+      undef_method :current_user
       def current_user
         Kracken::SpecHelper.current_user
       end