Upgrade to Symfony 3.4

Integrated 0.8 ships with Symfony 3.4. Follow the upgrade guides from Symfony when upgrading your code from Symfony 2.8 to 3.4:

• https://github.com/symfony/symfony/blob/3.4/UPGRADE-3.0.md

• https://github.com/symfony/symfony/blob/3.4/UPGRADE-3.1.md

• https://github.com/symfony/symfony/blob/3.4/UPGRADE-3.2.md

• https://github.com/symfony/symfony/blob/3.4/UPGRADE-3.3.md

• https://github.com/symfony/symfony/blob/3.4/UPGRADE-3.4.md

• https://symfony.com/doc/3.4/setup/upgrade_major.html

Other changes are:

• The Integrated bundles are combined in one repository. Load integrated/integrated as composer package

• The view directories within Integrated are now lowercase (following the Symfony best practices)

• For mongodb_options in parameters.yml you might need to replace "db" with "authSource" to specify the authentication database

• Uglyfyjs is not required any more, becuase of future Webpack migration