Add Application Setting to configure Container Registry token expire delay (default 5min)

This adds an option to configure Container Registry token expire delay. The default is set to 5mins (something that is also used by Docker Hub).

What is left:
* [x] Write test to check the expire_delay

Fixes: https://gitlab.com/gitlab-org/gitlab-ce/issues/17890

@stanhu I think that this should land in patch release of 8.8.

See merge request !4364

This is not needed when we specify a default.

Update docs: previous version is 8.7

The old version is 8.7.

See merge request !4288

Enable Wiki Page events from Webhook admin UI in a Project

* Added UI to enable page wiki events
* Documentation for this event in Webhooks page

Fixes #17506

--- 

![new_webhook_UI](/uploads/63ef24b4ccef13ac7a5fda83e9ce64ad/new_webhook_UI.png)

See merge request !4135

Merge branch 'make-container-registry-authentication-service-compatible-with-older-docker' into 'master'

Make authentication service for Container Registry to be compatible with < Docker 1.11

This removes the usage of `offline_token` which is only present when using `Docker 1.11.x` instead we relay on `scope`. This should make it compatible with any client starting from 1.6 (I did test only 1.8 and up).

Right now we return 403 if unauthorized user doesn't have access to anything. In all other cases we return token, but with empty `access`, which simply disallow requested action.



See merge request !4363

Fix typo

Add missing "of" to CI YAML docs.

[ci skip]

See merge request !4331

Fix various documentation typos and spelling mistakes

[ci skip]

See merge request !4345

Add missing steps in update docs

Fixes #18009

[ci skip]

See merge request !4365

Enable Style/SpaceBeforeComma rubocop cop

No spaces before commas.

See #17478

See merge request !4360

Enable Performance/TimesMap Rubocop cop

Use Array.new with a block instead of `.times.collect` / `.times.map`.

See #17478

See merge request !4357

Enable Style/NegatedIf Rubocop cop

Favor `unless` over `if` for negative conditions (or control flow ||).

```ruby
# bad
do_something if !some_condition
# bad
do_something if not some_condition

# good
do_something unless some_condition
# good
some_condition || do_something
```

See #17478

See merge request !4355

Enable Lint/LiteralInCondition rubocop cop

Detects literals used in conditions.

See #17478

See merge request !4354

Enable Style/MultilineIfThen rubocop cop

Do not use then for multi-line if.

See #7478.

See merge request !4353

Enable Style/MethodDefParentheses rubocop cop

Use def with parentheses when there are parameters.

See #17478

See merge request !4352

Enable Style/IndentAssignment Rubocop style cop

Checks the indentation of the first line of the right-hand-side of a multi-line assignment.

See #17478

See merge request !4348

Enable Style/WhileUntilDo rubocop style cop

Checks for redundant `do` after `while` or `until`.

See #17478

See merge request !4350

Enable Style/EndOfLine Rubocop style cop

Use Unix-style line endings.

Removed carriage return character from end of each line in `app/controllers/projects/find_file_controller.rb`

See #17478

See merge request !4347

Enable Lint/BlockAlignment Rubocop cop

See #17478

See merge request !4346

Enable Style/RedundantParentheses rubocop cop

Checks for parentheses that seem not to serve any purpose.

See #17478 

See merge request !4361

Enable Style/SpaceBeforeComment rubocop cop

See #17478 

See merge request !4358

Enable Style/SpaceAfterMethodName rubocop cop

Do not put a space between a method name and the opening parenthesis  in a method definition.

See #17478

See merge request !4359

See #17478

No spaces before commas.

See #17478

See #17478

See #17478

Use Array.new with a block instead of `.times.collect` / `.times.map`.

See #17478

Favor `unless` over `if` for negative conditions
(or control flow ||).

See #17478

Checks of literals used in conditions.

See #17478