Clear project and user information from the context for cron-workers
As part of #67 (closed)
Jobs scheduled from Cron take no arguments, so they are inherently not scoped to a project/user/namespace. Though they could be triggered from a request, as we've seen in #90 (closed)
These jobs should always clear their these fields from the context and there should be a way to define context at runtime in a job to make up for this.