Issue #1920902 by neclimdul, larowlan, alexpott, chx, sun, jthorson, damiankloip, Berdir, Mixologic, YesCT, hussainweb, rcaracaus, cweagans, catch, jibran, msonnabaum, dawehner, webchick, anavarre, heyrocker: Add a Drupal Yaml wrapper so we can default to PECL Yaml component if it is available