run: set up archive dir and logger output sooner

Signed-off-by: Sage Weil <sage@inktank.com>
test
Move logging setup out of main()
run: write info.yaml on job start

Include basic metadata bout the job.

Signed-off-by: Sage Weil <sage@inktank.com>
Add exception hook
Pretty-up write_initial_metadata; s/run/name/
Don't print colon if there's no exception message. Also, remove testing
exception.