Fixed storing and loading nulls and booleans in Redis

asArray will not include null valued keys

fixes #1311

Fixes #5126

Removed `form` as a parameter to the events since it can be retrieved using `$grid.find('form.gridview-filter-form')`.

Events `beforeFilter.yiiGridView` and `afterFilter.yiiGridView` javascript events created for advanced use cases.

Trigger a new `filter.yiiGridView` event for yii grid view after grid filters are applied. This will enable developer to code a lot of use cases based on the grid filtering event. The filter `$form` can be accessed as a parameter to the event.

If you don't want to install command-line utils globally, you have to specify it's paths.

    public $commands = [
        'styl' => ['css', '@app/node_modules/bin/stylus < {from} > {to}'],
    ];

close #5130

- 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.

Translate spanish docs

fixes #5119

fixes #5104, fixes #5101