[4.3] New updater

### What we want?
Good, simple system for handling newscoop updates. Features:
* Notifications about new wersion
* Update database
* Update code
* Install new vendors
* Clear cache
* Small update packages - update Newscoop from zip file.

### How this should work?
For handling versions we can use Doctrine Migrations, in up and down methods we can set database changes and other.
We need provide a way for simple releasing maintenance page (we should create one). Whole code should be easy replaceable (without things like conf/upgrade.php file). We should always have rollback method.

Upgrade file should be independent and have login form like any other admin page in Newscoop.
On that page we need have information about current version, description for update and update button with upgrade porcess  output window.

### TO DO:
* check for newscoop installed version and decide if update.

Installation should provide `newscoop_migration_versions` table with current database/newscoop version. Upgrade script should check that version and run update if new versions exists.

We can connect it with mine own project for php applications generic updater (https://github.com/ahilles107)