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

@@ -104,13 +104,6 @@ test:install:
     - gdk run &
     - sleep 30
     - curl -f --retry 10 --retry-delay 5 http://127.0.0.1:3000/
-    - kill $! && fg
-    - 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/
 
 test:update:
   image: $TEST_IMAGE
@@ -123,7 +116,7 @@ test:update:
     when: always
   script:
     - source /home/gdk/.bash_profile
-    - gem install gitlab-development-kit
+    - gem install gitlab-development-kit 
     - cd /home/gdk
     - gdk init
     - cd gitlab-development-kit
@@ -135,11 +128,3 @@ test:update:
     - sleep 30
     - curl -f --retry 10 --retry-delay 5 http://127.0.0.1:3000/
     - gdk update
-    - kill $! && fg
-    - 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