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

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2343035 by fago, dawehner, larowlan, ianthomas_uk, cilefen, hussainweb, Miroling, jibran, beejeebus, dashaforbes, webmozart, klausi: Upgrade validator integration for Symfony versions 2.5+