Remove an unused helper

Use 'appstream-util status' now...
Remove an unused helper

Use 'appstream-util non-package-yaml' now...
Remove the python extractor guts

This has been superceeded by the createrepo_as project.
Remove logging support in fedora-download-cache
Add the GStreamer AppStream descriptions here for the non-free codecs

This ensures we can show a link to the Fedora wiki if the user types in some
search terms. The description is only shown in the non-free repo is enabled
and the package can be resolved on the local system.