We want to run CI with rails 4 for a short-term (until we are sure that
we will ship with rails 5). The problem is that rails 4 can not handle
rails 5 schema.rb properly - specifically `t.index` directive can not
handle multiple indexes on the same column.

Because combination of rails 4 + rails 5 schema will be used
only in CI for a short-term, we can just ignore these incompatibility
failures. This patch adds `rails5` helper for specs.

* add_index replaced with t.index
* intiger(size 8) replaced with bigin

* similar to rails 5 it assures that index length is set for blob
  columns also in rails 4
* it also ignores multiple definitions of indexes for mysql, for some
  tables we define multiple indexes on the same set of columns, but with
  different parameters (opclasses, where), these are not supported by
  mysql adapter so the second definition of index is skipped

CI jobs will be triggered both with rails 4 and 5
to make sure we keep backward compatibility if it turns out
we have to switch back to rails 4.

Rails 4 jobs are not allowed to fail for now, these jobs will be
removed in a follow-up MR next cycle.

* updates Gemfile
* uses Rails 5 unless explicitly disable

CE upstream - 2018-11-14 11:23 UTC

See merge request gitlab-org/gitlab-ee!8445

removed gcp_clusters table and keys

# Conflicts:
#	db/schema.rb

[ci skip]

Revert "Merge branch 'revert-drop-gcp-clusters-table' into 'master'"

See merge request gitlab-org/gitlab-ce!23020

Avoid returning deployment metrics url to MR widget when the deployment is not successful

Closes #53870

See merge request gitlab-org/gitlab-ce!23010

Track Kubernetes errors using Sentry

Closes #53922

See merge request gitlab-org/gitlab-ce!23026

Merge branch '8340-use-iid-instead-of-id-when-displaying-link-to-issue-on-group-security-dashboard' into 'master'

Resolve "Use iid instead of id when displaying link to issue on Group Security Dashboard"

Closes #8340

See merge request gitlab-org/gitlab-ee!8357

CE upstream - 2018-11-14 09:21 UTC

See merge request gitlab-org/gitlab-ee!8441

Update comment in Auto-DevOps.gitlab-ci.yml

See merge request gitlab-org/gitlab-ce!23013

Adds documentation of git trace when git push/pull times out

See merge request gitlab-org/gitlab-ce!23016

[EE] Fix a bug where internal email pattern wasn't respected

Closes gitlab-ce#52940

See merge request gitlab-org/gitlab-ee!8421

Fix a bug where internal email pattern wasn't respected

Closes #52940

See merge request gitlab-org/gitlab-ce!22516

CE upstream - 2018-11-14 08:21 UTC

See merge request gitlab-org/gitlab-ee!8438

Update events.md.

See merge request gitlab-org/gitlab-ce!23021

Add docs for setting up external Prometheus

Closes #40949 and #37255

See merge request gitlab-org/gitlab-ce!22831

Add docs for the tracing mvc

Closes #4753

See merge request gitlab-org/gitlab-ee!8359

CE upstream - 2018-11-14 05:33 UTC

Closes gitlab-ce#41825

See merge request gitlab-org/gitlab-ee!8436

CE upstream - 2018-11-13 17:21 UTC

Closes gitlab-ce#53919

See merge request gitlab-org/gitlab-ee!8429

Update draft comments design to match new design

Closes #8345

See merge request gitlab-org/gitlab-ee!8405