Test against Ruby 2.5 (#173)

Merge pull request 173

Author: jekyllbot

.rubocop.yml

@@ -2,7 +2,7 @@ inherit_gem:
   jekyll: .rubocop.yml
 
 AllCops:
-  TargetRubyVersion: 2.1
+  TargetRubyVersion: 2.2
   Exclude:
     - vendor/**/*
 

.travis.yml

@@ -1,17 +1,17 @@
 language: ruby
-before_script: bundle update
-script: "script/cibuild"
 sudo: false
 cache: bundler
-
 matrix:
   include:
     - # GitHub Pages
-      rvm: 2.4.0
+      rvm: 2.4.2
       env: GH_PAGES=true
-
 rvm:
+  - 2.5
   - 2.4
   - 2.3
   - 2.2
-  - 2.1
+before_install:
+- gem update --system
+before_script: bundle update
+script: script/cibuild

jekyll-redirect-from.gemspec

@@ -23,9 +23,9 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_runtime_dependency "jekyll", "~> 3.3"
-  spec.add_development_dependency "bundler", "~> 1.3"
+  spec.add_development_dependency "bundler", "~> 1.16"
   spec.add_development_dependency "jekyll-sitemap", "~> 1.0"
   spec.add_development_dependency "rake", "~> 12.0"
   spec.add_development_dependency "rspec", "~> 3.5"
-  spec.add_development_dependency "rubocop", "~> 0.51"
+  spec.add_development_dependency "rubocop", "0.51"
 end