- Add gdk-pixbuf-loader-rsvg Requires: needed, in order to be able
to convert .svg icons to pixmaps.

- Update to version 0.3.5:
+ New Features:
- Add new API required for firmware support.
- Add new API required for OSTree and xdg-app support.
- Add 'news-to-appdata' and 'appdata-to-news' cmds to
appstream-util.
- Support all of the yet-unreleased AppStream 0.9 spec.
+ Bugfixes:
- Add releases from the upstream AppData files.
- Allow short descriptions when validating in
releases.
- Correctly load descriptions from in AppData files.
- Fix a builder crash where a package depends on itself.
- Fix a crash when more than one thread tries to ensure the
same package.
- Fix DSO Linking error when built with --as-needed.
- Make the failed AppStream metadata optional.
- Make the icon tarball optional.
- Relax validation checks to allow empty release sections.
- Return the correct exit code from appstream-builder.
- Add gcab BuildRequires and Requires: needed for the cab
extraction of the new Firmware support.