Added mezzanine-smartling to third-party apps in README.
Added mezzanine-smartling to third-party apps in README.

douglaskastle/mezzanine,promil23/mezzanine,geodesign/mezzanine,nikolas/mezzanine,readevalprint/mezzanine,gradel/mezzanine,christianwgd/mezzanine,vladir/mezzanine,sjuxax/mezzanine,dovydas/mezzanine,viaregio/mezzanine,Cicero-Zhao/mezzanine,geodesign/mezzanine,nikolas/mezzanine,Cicero-Zhao/mezzanine,wbtuomela/mezzanine,christianwgd/mezzanine,viaregio/mezzanine,sjuxax/mezzanine,sjdines/mezzanine,dovydas/mezzanine,frankier/mezzanine,spookylukey/mezzanine,ryneeverett/mezzanine,frankier/mezzanine,douglaskastle/mezzanine,stephenmcd/mezzanine,stephenmcd/mezzanine,jerivas/mezzanine,molokov/mezzanine,readevalprint/mezzanine,dsanders11/mezzanine,douglaskastle/mezzanine,wbtuomela/mezzanine,eino-makitalo/mezzanine,ryneeverett/mezzanine,molokov/mezzanine,jerivas/mezzanine,dovydas/mezzanine,viaregio/mezzanine,spookylukey/mezzanine,eino-makitalo/mezzanine,sjdines/mezzanine,gradel/mezzanine,spookylukey/mezzanine,gradel/mezzanine,wbtuomela/mezzanine,geodesign/mezzanine,dsanders11/mezzanine,eino-makitalo/mezzanine,vladir/mezzanine,promil23/mezzanine,molokov/mezzanine,readevalprint/mezzanine,jerivas/mezzanine,vladir/mezzanine,promil23/mezzanine,sjdines/mezzanine,sjuxax/mezzanine,ryneeverett/mezzanine,stephenmcd/mezzanine,frankier/mezzanine,dsanders11/mezzanine,christianwgd/mezzanine,nikolas/mezzanine