- do proper page conversion steps

...bluebutton/presentation/DocumentConversionServiceImp.java

.../main/java/org/bigbluebutton/presentation/PngCreator.java

.../java/org/bigbluebutton/presentation/SvgImageCreator.java

.../java/org/bigbluebutton/presentation/TextFileCreator.java

...java/org/bigbluebutton/presentation/ThumbnailCreator.java

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

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

...ava/org/bigbluebutton/presentation/imp/PngCreatorImp.java

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

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

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