cleanup gemfile + introduce gitlab ci

* Remove some unneeded deps
* Add gitlab ci similar to how users has, although currently we do
  have any proper tests, it still checks something
* Introduce a ci task that runs the steps to prepare the app after
  checkout from git
2 jobs for add-ci-cleanup-gemfile in 4 minutes and 23 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed test #7703
container

00:02:10

 
  Prod Setup
failed prod_setup_check #7704
container

00:02:13

 
Name Stage Failure
failed
prod_setup_check Prod Setup
/opt/rh/rh-ruby25/root/usr/share/gems/gems/bundler-1.16.1/lib/bundler/cli.rb:18:in `start'
/opt/rh/rh-ruby25/root/usr/share/gems/gems/bundler-1.16.1/exe/bundle:30:in `block in <top (required)>'
/opt/rh/rh-ruby25/root/usr/share/gems/gems/bundler-1.16.1/lib/bundler/friendly_errors.rb:122:in `with_friendly_errors'
/opt/rh/rh-ruby25/root/usr/share/gems/gems/bundler-1.16.1/exe/bundle:22:in `<top (required)>'
/opt/rh/rh-ruby25/root/usr/bin/bundle:23:in `load'
/opt/rh/rh-ruby25/root/usr/bin/bundle:23:in `<main>'
(See full trace by running task with --trace)
Cleaning up file based variables
ERROR: Job failed: exit code 1