twitter: guess the content type when uploading
twitter: guess the content type when uploading

lcp/libsocialweb,ThomasBollmeier/libsocialweb-flickr-oauth,ThomasBollmeier/libsocialweb-flickr-oauth,lcp/libsocialweb,GNOME/libsocialweb,GNOME/libsocialweb,ThomasBollmeier/libsocialweb-flickr-oauth,GNOME/libsocialweb,lcp/libsocialweb