not add empty file to uploaded files
not add empty file to uploaded files

Change-Id: Ia4b81dc6671e5dca2e8e76d7a4d6a6388257082d
Reviewed-on: http://cr.qtquick.me/510
Tested-by: http://ci.qtquick.me/
Reviewed-by: Tasuku Suzuki <42980d970444f9101663582e70cd53623b3238b4@gmail.com>
Tested-by: Tasuku Suzuki <42980d970444f9101663582e70cd53623b3238b4@gmail.com>

qt-users-jp/qthttpserver,qt-users-jp/qthttpserver