Add testify as test helpers

Force install bunder

See merge request gitlab-org/gitlab-shell!272

This avoids errors like:

$ gem install --bindir /usr/local/bin bundler -v "$INSTALL_BUNDLER_VERSION"
ERROR:  Error installing bundler:
	"bundle" from bundler conflicts with /usr/local/bin/bundle

Remove unused vendored code

See merge request gitlab-org/gitlab-shell!265

Specify bundler 1.17 for ruby 2.1 and 2.2

See merge request gitlab-org/gitlab-shell!271

Make better use of constants in lib/gitlab_shell.rb

See merge request gitlab-org/gitlab-shell!269

Gitaly hook transistion changes

See merge request gitlab-org/gitlab-shell!268

Fix rspec deprecation warning

See merge request gitlab-org/gitlab-shell!267

Fix spec failure with Ruby 2.5

See merge request gitlab-org/gitlab-shell!266

Handle push options

See merge request gitlab-org/gitlab-shell!166

See the discussion on gitlab-org/gitlab-shell!166

https://github.com/rubocop-hq/ruby-style-guide#module-function

push_opts[] is named as such so that it becomes an array in the
GitLab internal Grape::API params hash. If it were named push_opts, only
the final (scalar) push_opts parameter would be present.

Also update specs to include push_opts parameter:
- gitlab_post_receive_spec
- gitlab_net_spec for the internal API change

This module is responsible for converting the GIT_PUSH_OPTION_*
environment variables into an array.

See https://gitlab.com/gitlab-org/gitlab-ce/issues/18667

Remove unused lib/names_helper.rb

See merge request gitlab-org/gitlab-shell!173

This reverts merge request !257

Upgrade to Ruby 2.5.3

See merge request gitlab-org/gitlab-shell!257

As of 7eb45672, NamesHelper is no longer used.

Vendor updates

See merge request gitlab-org/gitlab-shell!264

Revert "Merge branch 'zj-rename-gitalypb' into 'master'"

See merge request gitlab-org/gitlab-shell!263

This reverts merge request !262

Upgrade gitaly Client dependency

See merge request gitlab-org/gitlab-shell!262

The client now has TLS support. So this gets pulled into this component.
To make it work, we have to upgrade the proto too.

Release v8.4.3

See merge request gitlab-org/gitlab-shell!259

Remove circular dependency between HTTPHelper and GitlabNet

Closes #169

See merge request gitlab-org/gitlab-shell!258

HttpHelper depended on exceptions defined in GitLabNet, but GitLabNet
included HttpHelper. Specs in Ruby 2.5 were breaking as a result of
Action::Custom not able to reference constants in GitLabNet:
https://gitlab.com/gitlab-org/gitlab-shell/-/jobs/126362702.

Closes https://gitlab.com/gitlab-org/gitlab-shell/issues/169

Release v8.4.2

See merge request gitlab-org/gitlab-shell!255

Include LFS operation when requesting auth

See merge request gitlab-org/gitlab-shell!254