Complete the list of programs to remove with "clean"
Allow O2wUniverse.of_repositories during staging

This function may fail due to a discrepancy between the installed OPAM
version (say compiled from the Git repository) and the opam2web
package.  This should not hinder testing the site on a local machine,
it should only fail on the server.
Use SVG version of RSS icon when possible
Depend on opam_update_list and not the program generating it

It prevents the file to be used while it is generated provoking the
following error "execvp: script/generate_opam_update_list: Text file
busy" when compiling with "make -j".