Merge branch 'patch-4' into 'master'

Update Ruby version to 2.3 in Requirements

According to the [GitLab 8.11 release notes](https://about.gitlab.com/2016/08/22/gitlab-8-11-released/), Ruby 2.3 is now supported and recommended. Update the documentation accordingly.

See merge request !5965

README.md

@@ -69,7 +69,7 @@ Instructions on how to start GitLab and how to run the tests can be found in the
 GitLab is a Ruby on Rails application that runs on the following software:
 - Ubuntu/Debian/CentOS/RHEL
-- Ruby (MRI) 2.1
+- Ruby (MRI) 2.3
 - Git 2.7.4+
 - Redis 2.8+
 - MySQL or PostgreSQL

doc/install/requirements.md

@@ -32,7 +32,7 @@ Please consider using a virtual machine to run GitLab.
 ## Ruby versions
-GitLab requires Ruby (MRI) 2.1.x and currently does not work with versions 2.2 or 2.3.
+GitLab requires Ruby (MRI) 2.3. Support for Ruby versions below 2.3 (2.1, 2.2) will stop with GitLab 8.13.
 You will have to use the standard MRI implementation of Ruby.
 We love [JRuby](http://jruby.org/) and [Rubinius](http://rubini.us/) but GitLab