fixes #5155

- use default application formatting for the date value
- auto adjust to application language and format setting changes
- be consistent with formatter and date validator

fixes #1551

- in composer the `~` operator is just a shortcut for `~1.0` = `>=1.0.0,<2.0.0`
  it does not prevent dev versions to be installed but neither does `1.*`
- dev versions are constrolled via `minimum-stability` setting and the
  `@dev`, `@beta`, `@stable`,... settings.
- setting bower packages that ship compiled files only with the stable
  release to use `@stable` in composer.json of the applictaions. This
  setting can be removed when we remove the `minimum-stability=dev`
  setting after GA.

Fixes #3687: Default `sourceLanguage` and `language` are now `en-US` in order for i18n formatter to work correctly

Second Example should start with ProgressBar::begin not ProgressBar::widget

Fix https://github.com/yiisoft/yii2/issues/2562

fixes #2514