Forbid scripting for wiki files

Wiki files (not pages - files in the repo) are just sent to the browser
with whatever content-type the mime_types gem assigns to them based on
their extension. As this is from the same domain as the GitLab
application, this is an XSS vulnerability.

Set a CSP forbidding all sources for scripting, CSS, XHR, etc. on these
files.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/17298.

See merge request !1969

Remove 'unscoped' from project builds selection

This is a fix for this security bug: https://gitlab.com/gitlab-org/gitlab-ce/issues/18188

/cc @kamil @grzegorz @stanhu

See merge request !1968

[ci skip]

Prevent privilege escalation via notes API

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15577

See merge request !1964

This reverts commit 550f9a74.

Fix vulnerability that leaks private labels and milestones

This fixes vulnerability that leaks information about private labels and milestones because of  insecure direct object reference in issueable create service.
This affects merge requests and issues.

See https://gitlab.com/gitlab-org/gitlab-ce/issues/15439

This MR introduces additional check that rejects labels and milestone that does not belong to the same project issue/merg request does.

`IssuableBaseService` may benefit from encapsulating filters in separate class/module, which then may improve coherency in this class.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15439

See merge request !1954
Signed-off-by: Rémy Coutable <remy@rymai.me>

Prevent users from deleting Webhooks via API they do not own

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15576

See merge request !1959
Signed-off-by: Rémy Coutable <remy@rymai.me>

Prevent XSS via custom issue tracker URL

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/15437

See merge request !1955
Signed-off-by: Rémy Coutable <remy@rymai.me>

Prevent information disclosure via milestone API

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15579

See merge request !1961

Prevent information disclosure via new merge request page

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15591.

See merge request !1963

Prevent privilege escalation via "impersonate" feature

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15548

See merge request !1956

Prevent information disclosure via snippet API

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15580

See merge request !1958

Fixes XSS injection

REF: https://gitlab.com/gitlab-org/gitlab-ce/issues/15434

**Without the fix**

![xss1](/uploads/0a7b0b15fb87066965a7c73f1dbaa815/xss1.gif)


**With the fix**

![xss2](/uploads/473cfa0aa80656f24c58aebf1fd97fff/xss2.gif)


See merge request !1952

Fixes window.opener bug

Adds `noreferrer` value to rel attribute for external links

REF: https://gitlab.com/gitlab-org/gitlab-ce/issues/15331

See merge request !1953

See https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1948

Fix 2FA authentication spoofing
Signed-off-by: Rémy Coutable <remy@rymai.me>

[ci skip]
Signed-off-by: Rémy Coutable <remy@rymai.me>

Closes #13957

Bump Git version requirement to 2.7.4 (for 8.4)

[ci skip]

See merge request !3283

[ci skip]

Fix missing gitlab_git version bump

Closes #13430 

See merge request !2811

Closes #13430

Bump gitlab_git to ~> 7.2.24

bump gitlab_git to ~> 7.2.24 (closes: #13245)

See merge request !2772

Add notice about variables in build log

Related to: https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1942

[ci skip]

See merge request !2761

[ci skip]

Fix timeout issue for rake task gitlab:backup:create

This is a fix for a database timeout which can occur when the backup
create task is taking very long (1-2 hours).
It seems that ActiveRecord is loosing the connection after a hour
idleness and need to be reconnected before use.

See merge request !2757

Limit guest access builds

This is https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1942 for ce-stable

See merge request !1943