Revert "Issue #2712647 by klausi, catch, slasher13, jibran, Manuel Garcia, alexpott, naveenvalecha, neclimdul, dawehner, Wim Leers, pounard: Update Symfony components to ~3.1"

This reverts commit a55b8ef1.

Issue #2712647 by klausi, catch, slasher13, jibran, Manuel Garcia, alexpott, naveenvalecha, neclimdul, dawehner, Wim Leers, pounard: Update Symfony components to ~3.1

Issue #2650812 by Wim Leers, Fabianx, Gábor Hojtsy, chx, dawehner, alexpott: Container::has() doesn't work for service aliases (consequently, decorating services doesn't work)

Issue #2572777 by andypost, alexpott, attiks, andriyun: Fix 'Squiz.Strings.ConcatenationSpacing' coding standard

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2497243 by Fabianx, znerol, fgm, Wim Leers, darol100, jhedstrom, hussainweb, pfrenssen, neclimdul, jibran, Nitesh Sethia, dawehner, chx, catch, benjy, Aki Tendo: Replace Symfony container with a Drupal one, stored in cache