Update Japanese translations

Updated: qtbase, assistant, designer, linguist, qtdeclarative,
        qtmultimedia, qtquickcontrols
Added: qtserialport, qtwebsockets

Change-Id: I41877e7d81206b737a702c13d01846fc1335beb0
Reviewed-by: Naoki Matsumoto <nekomatu@gmail.com>
Reviewed-by: Tasuku Suzuki <stasuku@gmail.com>
Reviewed-by: Takayuki ORITO <iori.ayane@gmail.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>