Add ABRT plugins and a dependency

rubygem-foreman_abrt
rubygem-smart_proxy_abrt
rubygem-satyr

NOTE: I used `smart_proxy_pulp` as a template, which is added under `foreman-plugins-nightly-rhel6` in `tito.props`. If I understand correctly the rhel6 plugins are built in `ruby193` collection, however the proxy itself is built without the collection - won't it lead to problems?
This dependency's missing from the gem, please ensure you add it to the gemspec (no need for this PR, but it should be in the next release.)