update Ruby version to 2.2.4 (latest previous stable) and update docs

.ruby-version

-2.1.7
+2.2.4

doc/ci/examples/test-and-deploy-ruby-application-to-heroku.md

@@ -56,12 +56,12 @@ gitlab-ci-multi-runner register \
   --non-interactive \
   --url "https://gitlab.com/ci/" \
   --registration-token "PROJECT_REGISTRATION_TOKEN" \
-  --description "ruby-2.1" \
+  --description "ruby-2.2" \
   --executor "docker" \
-  --docker-image ruby:2.1 \
+  --docker-image ruby:2.2 \
   --docker-postgres latest
 ```
 
-With the command above, you create a runner that uses [ruby:2.1](https://registry.hub.docker.com/u/library/ruby/) image and uses [postgres](https://registry.hub.docker.com/u/library/postgres/) database.
+With the command above, you create a runner that uses [ruby:2.2](https://registry.hub.docker.com/u/library/ruby/) image and uses [postgres](https://registry.hub.docker.com/u/library/postgres/) database.
 
 To access PostgreSQL database you need to connect to `host: postgres` as user `postgres` without password.

doc/ci/yaml/README.md

@@ -33,7 +33,7 @@ The YAML syntax allows for using more complex job specifications than in the
 above example:
 
 ```yaml
-image: ruby:2.1
+image: ruby:2.2
 services:
   - postgres
 

doc/development/ci_setup.md

@@ -26,7 +26,7 @@ We use [these build scripts](https://gitlab.com/gitlab-org/gitlab-ci/blob/master
 # Build configuration on [Semaphore](https://semaphoreapp.com/gitlabhq/gitlabhq/) for testing the [GitHub.com repo](https://github.com/gitlabhq/gitlabhq)
 
 - Language: Ruby
-- Ruby version: 2.1.2
+- Ruby version: 2.2.4
 - database.yml: pg
 
 Build commands

doc/install/installation.md

@@ -116,9 +116,9 @@ Remove the old Ruby 1.8 if present
 Download Ruby and compile it:
 
     mkdir /tmp/ruby && cd /tmp/ruby
-    curl -O --progress https://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.7.tar.gz
-    echo 'e2e195a4a58133e3ad33b955c829bb536fa3c075  ruby-2.1.7.tar.gz' | shasum -c - && tar xzf ruby-2.1.7.tar.gz
-    cd ruby-2.1.7
+    curl -O --progress https://cache.ruby-lang.org/pub/ruby/2.2/ruby-2.2.4.tar.gz
+    echo 'e2e195a4a58133e3ad33b955c829bb536fa3c075  ruby-2.2.4.tar.gz' | shasum -c - && tar xzf ruby-2.2.4.tar.gz
+    cd ruby-2.2.4
     ./configure --disable-install-rdoc
     make
     sudo make install