Remove files that are not used in the project

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Author: dzaporozhets

.rubocop.yml

@@ -2,17 +2,9 @@
 AllCops:
  Exclude:
  - 'spec/**/*'
- - 'features/**/*'
  - 'vendor/**/*'
- - 'db/**/*'
  - 'tmp/**/*'
  - 'bin/**/*'
- - 'lib/backup/**/*'
- - 'lib/tasks/**/*'
- - 'lib/email_validator.rb'
- - 'lib/gitlab/upgrader.rb'
- - 'lib/gitlab/seeder.rb'
- - 'lib/vendor/**/*'
  - 'hooks/**/*'
  - 'Guardfile'