better censorship of overall journals

Sometimes journal_events have a :project method, but no :project_id method.
We still use event.project_id if possible (it's faster) and fallback to
event.project.id.
Merge branch 'feature/rails3' into feature/rails3_repair_activity
fix typo in activity event filter
test wiki activity with a cuke
Merge pull request #300 from opf/feature/rails3_repair_activity

better censorship of overall journals