Closes #97 - Adds selection of ids and relations besides the counts
Merge pull request #98 from geeksoflondon/interactable_relation_filters

Closes #97 - Adds selection of ids and relations besides the counts
Merge branch 'master' into barcampberk
Refactoring #attendee_status to use the new interactable methods
Fixing BCB tickets so they have attended_saturday attended_sunday