fix most of warnings

app/controllers/admin/projects_controller.rb

app/controllers/admin/users_controller.rb

app/controllers/profiles/keys_controller.rb

app/controllers/projects/deploy_keys_controller.rb

app/controllers/projects/hooks_controller.rb

app/models/project.rb

app/models/project_team.rb

app/models/user.rb

app/views/projects/issues/_form.html.haml

app/views/projects/merge_requests/_form.html.haml

lib/api/namespaces.rb

lib/api/users.rb

spec/contexts/fork_context_spec.rb

spec/controllers/application_controller_spec.rb

spec/helpers/application_helper_spec.rb

spec/helpers/gitlab_markdown_helper_spec.rb

spec/helpers/notifications_helper_spec.rb

spec/helpers/search_helper_spec.rb

spec/helpers/tab_helper_spec.rb

spec/lib/extracts_path_spec.rb