Enhancements to Contributors appearing in Feeds

* Contributors without URI will no longer be displayed in the feeds
* Added an option to filter appearing of contributors by role and group
update readme
Merge branch 'release-1-10-14' into contrib_feeds
fix translation and add description
rename a hook

Hook names should be chosen in regard to the *provider*, not the
*consument*, since there may be a lot of different consuments.

/cc @chemiker
apply contributor filter to feed items too

because I guess this is how it was intended @chemiker ?
refactor: remove code duplication