Merge branch 'pw/git-p4-jobs'

Teach "git p4" to notice "Jobs:" in the log message and relay it to
Perforce to trigger its "jobs" support.

# By Pete Wyckoff
* pw/git-p4-jobs:
git p4: notice Jobs lines in git commit messages
git p4 test: refactor marshal_dump
git p4: remove unused P4Submit interactive setting