Fixes #5070: Gii controller generator should use controller class name instead of controller ID to specify new controller

Revert "Fixes #3760: Gii model generator now imports classes when necessary instead of using fully qualified class names"

This reverts commit 0c8faedd.

Fixes #3760: Gii model generator now imports classes when necessary instead of using fully qualified class names

Fixes #5587: `json_encode` is now used with `JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE` where it makes sense, also it is now default for `Json::encode()`

Improved checks where substr_compare is used, replaced more substr + comapre cases with substr_compare

reverts 45e4973a

PR #3676

Alternatively, if statement could be: if(substr($column->dbType, 0, 4) === 'enum'), however expected implemented option to be more robust across other database formats.

Created after followup on this issue:  https://github.com/yiisoft/yii/issues/292#issuecomment-44780779

```
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
```

To comply with the docs RE namespace usage:
https://github.com/yiisoft/yii2/blob/master/docs/guide/extend-creating-extensions.md