MigrateCommand enhancement. `all` option added for `down` action.
CHANGELOG updated
Comments updated
CHANGELOG fixed
changed comments #3446
fixed console errorHandler class
Merge pull request #3447 from lynicidn/patch-1

changed comments #3446
rest guide WIP [skip ci]
docs about multiple grids on one page.
guide WIP [skip ci]
Fixes #3458: Fixed the bug that the image rendered by `CaptchaAction` was using a wrong content type
Allow fast finishing
Small changes according to the class reference

It looks like this values are supposed to be in different order due to the class reference and practice.
Merge pull request #3463 from DaSourcerer/travis-ci

[travis-ci] Allow fast finishing
Merge pull request #3464 from it3rmit/patch-4

Small changes according to the class reference
Update various typos and grammar
Merge pull request #3465 from kartik-v/patch-2

Update various typos and grammar
MigrateController refactoring
Merge PR #3421 branch 'migrate-command-enhancement' of https://github.com/creocoder/yii2

* 'migrate-command-enhancement' of https://github.com/creocoder/yii2:
  MigrateController refactoring
  CHANGELOG fixed
  Comments updated
  CHANGELOG updated
  MigrateCommand enhancement. `all` option added for `down` action.

Conflicts:
	framework/CHANGELOG.md