Add support of Rails 5

This MR adds support of running GDK on Rails 5.

We are migrating to it now.

The current commands work as before.
New commands for Rails 5: gdk run 5 and gdk run app 5.

.gitlab-ci.yml

@@ -136,11 +136,12 @@ test:update:
     - sleep 30
     - curl -f --retry 10 --retry-delay 5 http://127.0.0.1:3000/
     - gdk update
-    - $(ps aux | grep 'foreman' | grep -v grep | awk '{print $2}')
+    - kill $(ps aux | grep 'foreman' | grep -v grep | awk '{print $2}')
     - sleep 5
     - killall node || true
     - cd /home/gdk/gitlab-development-kit/gitlab
     - BUNDLE_GEMFILE=Gemfile.rails5 bundle install --jobs $(nproc) --without production --without mysql
     - gdk run rails5 &
     - sleep 30
+    - curl -f --retry 10 --retry-delay 5 http://127.0.0.1:3000/
     - gdk update