GH-39: Update Ruby 2.1 to 2.5

Author: mrk21

Dockerfile

@@ -2,7 +2,7 @@
 # see: http://totem3.hatenablog.jp/entry/2017/08/13/133954
 
 # see: https://hub.docker.com/_/ruby/
-FROM ruby:2.1
+FROM ruby:2.5
 ENV LANG C.UTF-8
 
 RUN apt-get update -qq && apt-get install -y build-essential libpq-dev apt-utils tree vim less

README.rdoc

@@ -25,8 +25,8 @@ https://heartrails-rails4-example.herokuapp.com/
 
 動作環境
 ----
-- Ruby 2.1.1
-- Rails 4.1.4
+- Ruby 2.5.0
+- Rails 4.2.10
 - PostgreSQL 9.3
 - Memcached 1.5.4