Adding rotateByCopy to yii\log\FileTarget #3562

Looks good!

Question: Not sure about the point being made with components and
DatePicker. Please clarify if I misinterpreted.

fixes #2797

Fixes #3542: Removed requirement to specify `extensions` in application config

Conflicts:
	framework/CHANGELOG.md

[Travis CI] Include nightly HHVM builds into the build matrix

fixes #3578

Add $key to function parameter

This is a porting from yii framework version 1.
I need it to run functional tests with fixtures.

[ci skip] Updated pt-BR translation

RangeValidator typo fix

fixes #3539

```
vendor/bin/indent --spaces -r framework/
vendor/bin/indent --tabs -r . --pattern=*.json
vendor/bin/indent --spaces -r . --pattern=*.md
vendor/bin/indent --spaces -r . --pattern=yii.*.js
vendor/bin/indent --spaces -r . --pattern=*.css
```