Update .travis.yml (#520)

* Update Rubies to latest version.
* Add ruby-head as allow_failures.
  * It's good to know new version Ruby's issue as faster before the release.
  * fast_finish is to get the Travis result as faster
    without waiting the result of the "allow_failures" items.
    See https://blog.travis-ci.com/2013-11-27-fast-finishing-builds/
* Do hack for Ruby 1.9.3 and 2.0.0.
  Because the Rails 4.2 dependency's nokogiri latest version requires Ruby
  version >= 2.1.0.

Author: junaruga

.travis.yml

@@ -4,9 +4,11 @@ sudo: false
 rvm:
   - 1.9.3 # when removed, get rid of the before_script hack and also the one in application_generator.rb
   - 2.0.0
-  - 2.1.9
-  - 2.2.5
-  - 2.3.1
+  - 2.1.10
+  - 2.2.7
+  - 2.3.4
+  - 2.4.1
+  - ruby-head
 env:
   - RAILS_VERSION="~> 4.2.0"
   - RAILS_VERSION="~> 5.0.0"
@@ -16,8 +18,12 @@ matrix:
       env: RAILS_VERSION="~> 5.0.0"
     - rvm: 2.0.0
       env: RAILS_VERSION="~> 5.0.0"
-    - rvm: 2.1.9
+    - rvm: 2.1.10
       env: RAILS_VERSION="~> 5.0.0"
+  allow_failures:
+    - rvm: ruby-head
+  fast_finish: true
 before_script:
   - "[ $TRAVIS_RUBY_VERSION = \"1.9.3\" ] && travis_retry gem install mime-types --version \"~> 2\" || true"
+  - "[ $TRAVIS_RUBY_VERSION = \"1.9.3\" -o $TRAVIS_RUBY_VERSION = \"2.0.0\" ] && travis_retry gem install nokogiri --version \"~> 1.6.8\" || true"
   - travis_retry gem install rails --version "$RAILS_VERSION"

lib/spring/test/application_generator.rb

@@ -92,6 +92,11 @@ def install_spring
 
         build_and_install_gems
 
+        # TO prevent nokogiri install error in application.bundle.
+        if RUBY_VERSION < "2.1.0"
+          append_to_file(application.gemfile, "gem 'nokogiri', '~> 1.6.8'")
+        end
+
         application.bundle
 
         FileUtils.rm_rf application.path("bin")