CI: Add a Rails 6 gemfile (allenwq#60)

* Add a Rails 6 gemfile

See allenwq#50

* CI: Expect there to be a Bundler

* CI: Use a matrix to describe builds

  - this is to be able to say Rails 6 does not run on 2.4

* README: Drop note about versions of Rails

.gitignore

@@ -10,3 +10,4 @@
 /spec/rails_app/log/*
 /.ruby-version
 /.idea/
+/gemfiles/*gemfile.lock

.travis.yml

@@ -1,9 +1,16 @@
 language: ruby
+
 rvm:
   - 2.4
   - 2.5
   - 2.6
 gemfile:
   - gemfiles/rails_5_2.gemfile
   - gemfiles/rails_5_1.gemfile
-before_install: gem install bundler
+  - gemfiles/rails_6_0.gemfile
+
+jobs:
+  exclude:
+    - rvm: 2.4
+      gemfile: gemfiles/rails_6_0.gemfile 
+

README.md

@@ -10,7 +10,7 @@ Letting [Devise](https://github.com/plataformatec/devise) support multiple email
 
 ## Getting Started
 
-Add this line to your application's `Gemfile`, _devise-multi_email_ has been tested with Devise 4.0 and rails 4.2:
+Add this line to your application's `Gemfile`:
 
 ```ruby
 gem 'devise-multi_email'

gemfiles/rails_6_0.gemfile

@@ -0,0 +1,5 @@
+source "https://rubygems.org"
+
+gem "rails", ">= 6.0.2.1", "< 6.1"
+
+gemspec path: "../"