Added automatic generating of unique slug value to `yii\behaviors\Sluggable`
Default event for `yii\behaviors\Sluggable` with `unique` enabled changed to 'insert'.
Created ArrayCache class

- can be used to enable caching in a request without the need for any storage
- useful for example in complex console tasks that should still be independed
Add rest-authentication.md to translate into Russian
Translated rest-authentication.md into Russian
Merge pull request #4685 from bevalorous/docs-guide-russian-translation

[ci skip] Docs guide russian translation: translated rest-authentication.md into Russian
`yii\behaviors\Sluggable` optimized
`yii\behaviors\Sluggable` simplified
`yii\behaviors\Sluggable::validateSlug()` fixed to respect updating record
merge with upstream
CHANGELOG updated
`yii\behaviors\Sluggable` adjusted
Merge pull request #4680 from yiisoft/array-cache

Created ArrayCache class
Improved test config

You can now customize test config without having uncommitted changes in
git.

issue #4687
improved unit test SKIP detection

issue #4687
fixed test break
try running against postgres 9.3 for #4672
Update README.md
Merge pull request #4675 from klimov-paul/4630-sluggable

Fix #4630: automatic generating of unique slug value to `yii\behaviors\Sluggable`
Model parameter added to `yii\behaviors\Sluggable::uniqueSlugGenerator` callback