receiver: Add type metadata to slugbuilder jobs
receiver: Add type metadata to slugbuilder jobs

Giving these jobs a type previously lead to the scheduler killing them
as they were not scaled in the release's formation, but the scheduler
now handles this by checking if the job has a type from the release, see
https://github.com/flynn/flynn/blob/v20160309.0/controller/scheduler/scheduler.go#L1159-L1163

Signed-off-by: Lewis Marshall <748e1641a368164906d4a0c0e3965345453dcc93@lmars.net>

benbjohnson/flynn,lmars/flynn,philiplb/flynn,lmars/flynn,lmars/flynn,philiplb/flynn,philiplb/flynn,benbjohnson/flynn,philiplb/flynn,benbjohnson/flynn,flynn/flynn,flynn/flynn,benbjohnson/flynn,flynn/flynn,lmars/flynn,lmars/flynn,flynn/flynn,benbjohnson/flynn,philiplb/flynn,flynn/flynn,benbjohnson/flynn