Added missing MIME types to mime.types file

application/vnd.openxmlformats-officedocument.spreadsheetml.template xltx
application/vnd.openxmlformats-officedocument.presentationml.slideshow ppsx
application/vnd.openxmlformats-officedocument.presentationml.presentation pptx
application/vnd.openxmlformats-officedocument.presentationml.slide sldx
application/vnd.ms-excel.addin.macroEnabled.12 xlam
application/vnd.ms-excel.sheet.binary.macroEnabled.12 xlsb