Ensure GithubImport::Client does not crash when the 'verify_ssl' config is not present

This fixes gitlab-org/gitlab-ce#14343 and !260 (merged) when verify_ssl is not present in the GitHub omniauth settings in gitlab.yml.

Settingslogic allow to access optional settings through the Hash notation: if the key is not present, it returns nil. In the present case this will let the Octokit::Client object use whatever default value it wants for the ssl option.

/cc @dbalexandre

@rymai Can you rebase? The failures should be fixed by https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/277, but I want to make sure we don't merge some other error by accident :)

Reassigned to @rymai

@DouweM Yes I will now!

Added 36 commits:

• 2a8a3e5f...ac0451df - 35 commits from branch master
• 7cfd685a - Ensure GithubImport::Client does not crash when the 'verify_ssl' config is not present

Enabled an automatic merge when the build for 7cfd685a succeeds

Status changed to merged

mentioned in commit acdccfba

Will go into 8.6.0-rc3.

Removed ~149424 label

mentioned in commit 2f69bb56

Does this config value need support in omnibus?

@stanhu I believe it's "already supported" since this value is inside the GitHub Omniauth hash (in gitlab_rails['omniauth_providers']). The issue was that the code was not handling gracefully the lack of this option.

@rymai Right, thanks.

mentioned in commit bdac5ddd

Mentioned in commit bdac5ddd

Mentioned in commit acdccfba

added Enterprise Edition label