init of advanced application now allows to specify answer for overwriting files  via init --overwrite=n

Fixes #1937: Fixed wrong behavior or advanced app's `init --env` when called without parameter actually specified

Removed error-block HTML class and related styles and used Bootstrap3 standard practice about errors instead

Fixes #1633: fixed scenarios for User model in advanced application allowing setting default values for User model

Advanced app template: moved database connection DSN, login and password to -local config not to expose it to VCS

1. It results in much smaller download and takes less disk space (25MB instead of 180MB for yii-basic + dependencies).
2. It requires less utilities to be installed (no VCS binaries required).
3. It takes less time to install dependencies.

to allow specific styling
also fixed an issue with gridview sort indicator css.

fixes #1000

fixes #1736

fixes #1717

Fixes #1597: Added `enableAutoLogin` to basic and advanced application templates so "remember me" now works properly

Backend should be always totally closed for indexing by search engine robots

we should not provide one in the package but developers should commit
them when starting a new project so that all share the same versions
and only explicit composer update command will change that.
Escpecially important when deploying to production.