Merge pull request #6150 from riadvice/better-error-logging

.../java/org/bigbluebutton/presentation/ImageToSwfSlide.java

...in/java/org/bigbluebutton/presentation/PdfToSwfSlide.java

...uebutton/presentation/PresentationUrlDownloadService.java

...on/presentation/handlers/Pdf2PngPageConverterHandler.java

...on/presentation/handlers/Pdf2SwfPageConverterHandler.java

...uebutton/presentation/handlers/PdfPageCounterHandler.java

...on/presentation/handlers/Png2SwfPageConverterHandler.java

...luebutton/presentation/handlers/SvgConversionHandler.java

...n/presentation/imp/ImageToSwfSlidesGenerationService.java

...gbluebutton/presentation/imp/Office2PdfPageConverter.java

...gbluebutton/presentation/imp/OfficeDocumentValidator.java

...button/presentation/imp/OfficeToPdfConversionService.java

.../bigbluebutton/presentation/imp/Pdf2SwfPageConverter.java

...va/org/bigbluebutton/presentation/imp/PdfPageCounter.java

...ton/presentation/imp/PdfToSwfSlidesGenerationService.java

...rg/bigbluebutton/presentation/imp/SvgImageCreatorImp.java

...rg/bigbluebutton/presentation/imp/TextFileCreatorImp.java

...g/bigbluebutton/presentation/imp/ThumbnailCreatorImp.java