[Rails5] Fix `undefined method 'downcase'` errors in requests specs

See merge request gitlab-org/gitlab-ee!5510

Adds Omniauth Provider for Group SAML

See merge request gitlab-org/gitlab-ee!5509

Port of jr-33320-lfs-settings-interface to EE

See merge request gitlab-org/gitlab-ee!5533

CE upstream - 2018-05-01 18:25 UTC

Closes #4922

See merge request gitlab-org/gitlab-ee!5535

# Conflicts:
#	app/helpers/auth_helper.rb
#	doc/api/discussions.md
#	lib/api/discussions.rb
#	spec/helpers/auth_helper_spec.rb
#	spec/requests/api/discussions_spec.rb

[ci skip]

Fix memory and performance issues in Karma test suite

Closes #45900 and #45806

See merge request gitlab-org/gitlab-ce!18658

Fix repository location in GitLab QA squash specs

See merge request gitlab-org/gitlab-ee!5528

Bump nokogiri to 1.8.2 in qa Gemfile

See merge request gitlab-org/gitlab-ce!18673

Use gitaly 0.96.2

See merge request gitlab-org/gitlab-ce!18670

CE upstream - 2018-05-01 00:27 UTC

See merge request gitlab-org/gitlab-ee!5524

Fix commit trailer rendering when Gravatar is disabled

Closes #45633

See merge request gitlab-org/gitlab-ce!18586

Resolves CVE-2017-18258

Use gitlab-workhorse 4.2.0

See merge request gitlab-org/gitlab-ce!18671

LFS can be enabled and disabled per project using the API by Masters
and Owners, but the UI is only available to Admins. The interface and
API should be consistent.

LFS can also be enabled and disabled per group using the API by Owners,
but the UI is only available to Admins. This interface should also be
consistent.

Additionally removes an unneeded check if 2FA interface, since the
interface is only available to Owners.

Closes #33320

Use persisted diff data instead fetching Git on discussions

Closes #44052

See merge request gitlab-org/gitlab-ce!18657

Resolve "Remove USE_SYSTEM_GIT_FOR_FETCH"

Closes #5224

See merge request gitlab-org/gitlab-ee!5525

Minor fix of disaster recovery doc

See merge request gitlab-org/gitlab-ee!5518

Add alpine mirrors while operating on k8s cluster

Closes gitlab-ee#4922

See merge request gitlab-org/gitlab-ce!18651

Resolve "Geo: Prometheus metrics for checksummed/verification is confusing"

Closes #5466

See merge request gitlab-org/gitlab-ee!5367

Merge request and commit discussions API

Closes #20901

See merge request gitlab-org/gitlab-ce!18537

[EE] Discussion API for merge requests and commits

See merge request gitlab-org/gitlab-ee!5469

Use Ruby methods, not Rails' String#first

See merge request gitlab-org/gitlab-ce!18669

[CE] Exclude LDAP from OmniauthCallbackController base methods

See merge request gitlab-org/gitlab-ce!18619