Update Ruby version to 2.3.1

.ruby-version

@@ -1 +1 @@
-2.3.0
+2.3.1

.travis.yml

@@ -3,7 +3,7 @@ bundler_args: "--without assets:development:production"
 cache: bundler
 language: ruby
 rvm:
-  - 2.3.0
+  - 2.3.1
 script:
   - bundle exec rake
   - bundle exec rubocop

Gemfile

@@ -1,5 +1,5 @@
 source 'https://rubygems.org'
-ruby '2.3.0'
+ruby '2.3.1'
 
 gem 'rails', '~> 4.2.6'
 

Gemfile.lock

@@ -238,7 +238,7 @@ DEPENDENCIES
   webmock
 
 RUBY VERSION
-   ruby 2.3.0p0
+   ruby 2.3.1p112
 
 BUNDLED WITH
    1.12.3