Add list of supported images format in .desktop file.

NOTE: Raw formats are missing.

data/desktop/ephoto.desktop

@@ -13,3 +13,4 @@ Icon=ephoto
 Terminal=false
 Type=Application
 Categories=Graphics;Viewer;
+MimeType=inode/directory;image/png;image/jpeg;image/pjpeg;image/x-xpixmap;image/tiff;image/svg+xml;image/svg+xml-compressed;image/gif;image/x-portable-anymap;image/x-portable-bitmap;image/x-portable-graymap;image/x-portable-pixmap;image/bmp;image/x-bmp;image/x-tga;image/vnd.wap.wbmp;image/webp;image/vnd.microsoft.icon;image/ico;image/x-ico;image/x-win-bitmap;image/vnd.adobe.photoshop;image/x-psd;application/pdf;application/x-pdf;image/pdf;application/postscript;image/x-xcf;image/x-compressed-xcf;