Previously all the formats was specified but none of them were being converted or detected .  But in my patch , it is able to detect and convert ppt pptm pptx formats .

So ,we can atleast add support for these formats .

Change-Id: I6083a9048ada870178753cd4ba523c9d3916cf11
Reviewed-on: https://gerrit.libreoffice.org/3617Reviewed-by: Tor Lillqvist <tml@iki.fi>
Tested-by: Tor Lillqvist <tml@iki.fi>