WebSubmit: title not required when creating PDF/A

• When during a conversion, a PDF/A file is generated e.g. from a PDF or from a PDF/A, if the title can not be guessed, and was not provided as a parameter, the conversion was failing with an exception. However an intermediate conversion to PDF/A might be used temporary to e.g. simply extract text from a PS file, when a proper converter for PostScript to text was not already existing. In this case it makes no sense to fail requiring no title. This is no longer the case. If the title can be upon calling the conversion, it will be used, otherwise, if necessary, it will be set in the PDF metadata as 'No title'.